U.S. DEPARTMENT OF THE INTERIOR
U.S. GEOLOGICAL SURVEY
This map and the accompanying dataset (asbestos_sites.xls) provide information on 51
natural occurrences of asbestos in Washington and Oregon, using descriptions found in the geologic
literature. Data on location, mineralogy, geology, and relevant literature for each asbestos site are
provided in the aforementioned digital file. Using the map and digital data in this report, the user can
examine the distribution of previously reported asbestos occurrences and their geologic
characteristics in the northwestern United States. This report is part of an ongoing study by the U.S.
Geological Survey to identify and map reported natural occurrences of asbestos in the United States,
which thus far includes reports of similar format for the Eastern United States (Van Gosen, 2005),
the Central United States (Van Gosen, 2006), the Rocky Mountain States (Van Gosen, 2007a), and
the Southwestern States (Van Gosen, 2008). These reports are intended to provide Federal, State, and
local government agencies and other stakeholders with geologic information on natural occurrences
The file asbestos_sites.xls was compiled through a systematic search of the geologic
literature. Although this asbestos dataset represents a thorough study of the published literature, it
cannot be construed as a complete list. An asbestos site was included only when the literature source
specifically mentioned asbestos and (or) described the commonly recognized asbestos minerals as
occurring in the asbestiform crystal morphology. No attempt was made to infer the presence of
asbestos if asbestos was not explicitly described. The user should refer to the references cited for
each asbestos site entry for descriptions of these occurrences. These asbestos occurrences were
reported to exist in outcrop exposures or rock exposed by exploration and mining operations. Note
that these site descriptions apply to the time of each report's publication. No field verification of the
sites was performed, nor were evaluations of potential exposure made at these sites. Many of the
sites are likely to have been subsequently modified by human activities since their description. For
example, since the time that the source literature was published, there may have been remediation of
the site or it may have been either exposed or covered by recent development.
What is Asbestos?
The history of asbestos discovery and usage is at least 5,000 years old, extending back to the
ancient civilizations in Greece and what is now Italy (see Ross and Nolan, 2003). Historically,
asbestos is a generic commercial-industrial term used to describe a group of specific silicate minerals
that form as long, very thin mineral fibers, which can form bundles. When handled or crushed,
asbestos bundles readily separate into individual mineral fibers. The special properties of
commercial-grade asbestos—long, thin, durable mineral fibers and fiber bundles with high tensile
strength, flexibility, and resistance to heat, chemicals, and electricity—have made it well suited for a
number of commercial applications (Bowles, 1955; Ross, 1981; Zoltai, 1981; Cossette, 1984; Ross
and others, 1984; Skinner and others, 1988). Asbestos has been primarily used for its insulating and
fire-resistant properties in many types of products (see Virta, 2006; Ross and Virta, 2001).
Currently, most commercial and regulatory definitions of asbestos include chrysotile, the
asbestiform member of the serpentine group, and several members of the amphibole mineral group,
including the asbestiform varieties of (1) riebeckite (commercially called crocidolite), (2)
cummingtonite-grunerite (commercially called amosite), (3) anthophyllite (anthophyllite asbestos),
(4) actinolite (actinolite asbestos), and (5) tremolite (tremolite asbestos). Other amphiboles are
known to occur in the fibrous and (or) asbestiform habit (Skinner and others, 1988), such as
winchite, richterite (Wylie and Huggins, 1980; Meeker and others, 2003), and fluoro-edenite
(Gianfagna and Oberti, 2001; Gianfagna and others, 2003).
Historically, chrysotile has accounted for more than 90 percent of the world's asbestos
production, and it presently accounts for over 99 percent of the world production (Ross and Virta,
2001; Virta, 2002). Mining of crocidolite and amosite deposits accounts for most of the other
asbestos production, and small amounts of anthophyllite asbestos have been mined in Finland and
the United States in the past (Ross and Virta, 2001; Van Gosen, 2005). Asbestos is no longer mined
in the United States, since the last U.S. asbestos operation closed in 2002; this mine worked a large
chrysotile deposit in the Coalinga district of central California.
Mounting evidence throughout the 20th century indicated that inhalation of asbestos fibers
caused respiratory diseases that have seriously affected many workers in certain asbestos-related
occupations (Tweedale and McCulloch, 2004; Dodson and Hammar, 2006). Airborne exposures to
asbestos have been linked to a number of serious health problems and diseases, including asbestosis,
lung cancer, and mesothelioma. Information on the health effects of asbestos is available online at
http://www.epa.gov/asbestos/ and http://www.atsdr.cdc.gov/asbestos/.
A number of United States governmental regulations address worker exposure to asbestos
released during the handling of introduced asbestos–containing products, in shipbuilding and general
construction sites, during building demolition or remodeling where asbestos containing materials
("ACM") may be encountered, and during the repair or replacement of commercial asbestos-based
products, such as some brake components. There also are regulations governing the release and
exposure of asbestos into the environment from manufacturing, mining, and other occupational sites.
Federal regulations are listed in the Code of Federal Regulations (available online at
Less straightforward is the regulation and management of the natural occurrences of
asbestos, often referred to as "naturally occurring asbestos" (NOA). These natural asbestos deposits
have gained the attention of regulatory agencies, health departments, and citizen groups. NOA
includes minerals described as asbestos that are found in-place in their natural state, such as in
bedrock or soils. Natural occurrences of asbestos are of concern due to potential exposures to
microscopic fibers that can become airborne if asbestos-bearing rocks are disturbed by natural
erosion or human activities (road building, urban excavations, agriculture, mining, crushing, and
milling, as just a few examples). The geology of asbestos and its application to identifying and
managing the natural deposits is explained in Van Gosen (2007b). Several examples of occupational
and environmental exposures to natural asbestos occurrences are described in Churchill and Hill
(2000), Nolan and others (2001), Clinkenbeard and others (2002), Gianfagna and others (2003),
Peipins and others (2003), Ross and Nolan (2003), Burragato and others (2005), Meeker and others
(2006), Sullivan (2007), and Horton and others (2008). United States Federal asbestos regulations do
not specifically address occupational exposures to natural occurrences of asbestos, nor do they
mention every variety of asbestiform amphibole.
The history and study of asbestos and its many complex issues are also discussed in
Campbell and others (1977), Ross (1981), Stanton and others (1981), Zoltai (1981), Levadie (1984),
Skinner and others (1988), Mossman and others (1990), Occupational Safety and Health
Administration (1992), Guthrie and Mossman (1993), van Oss and others (1999), Virta (2002),
Plumlee and Ziegler (2003), Dodson and Hammar (2006), and Fubini and Fenoglio (2007).
Natural Occurrences of Asbestos in the Northwestern United States Oregon's asbestos deposits. All of the reported natural asbestos occurrences in Oregon appear to be related to the alteration of an ultramafic rock, specifically olivine-rich rocks (dunite, peridotite) that were serpentinized. As a result, the reported asbestos-bearing localities in Oregon occur where ultramafic rocks are most abundant, which are the east-central and southwestern regions of the State (Krevor and others, 2009).
Asbestos was once commercially produced on a small scale from three locations in
Oregon—the Mount Vernon deposit in Grant County, the Raspberry Creek deposit in Jackson
County, and the L.E.J. Asbestos mine in Josephine County.
The Mount Vernon chrysotile deposit (site number 14) was worked by the Coast Asbestos
Company beginning in 1959, then again in 1961 and 1962 (inactive in 1960). The mine and its mill
were located on Beech Creek, about 3 miles northeast of Mount Vernon in Grant County. The
deposit consisted of thin, cross-fiber and slip-fiber chrysotile veins within a narrow,
northeast-trending body of serpentinite (Bright and Ramp, 1965). Wagner (1963) describes in detail
the pilot mill program that was operated on-site by Coast Asbestos Company; the fiber processing
involved many steps and was designed to potentially reach a capacity rate estimated at 5,000 pounds
of recovered fiber per 8-hour shift.
In 1943, along Raspberry Creek, Jackson County, a narrow lens of matted tremolite asbestos
was mined from shallow trenches (site number 17). The workings were on the south side of
Raspberry Creek, about a quarter mile to the west of the west fork of Evans Creek, Jackson County.
Reportedly, that year the mine produced 600 pounds of fiber that was sold at $600 per ton (Bright
and Ramp, 1965). The primary tremolite asbestos lens was described as no more than 1 foot in
width, occurring in serpentinite near a contact with metavolcanic rocks.
The L.E.J. Asbestos mine (site number 21) was located on the southwest side of Bolt
Mountain, about 6 miles southwest of Grants Pass in Josephine County. This mine produced a
relatively small amount of tremolite asbestos from cuts and trenches; about 3 tons of hand-sorted ore
was shipped in 1952 (Bright and Ramp, 1965). Slip-fiber tremolite associated with talc occurred in a
northeast-trending fracture or sheer zone, 4 inches to 2 feet thick, within a serpentinite.
Washington's asbestos deposits.
Washington contains many known asbestos occurrences,
many of which experienced past asbestos exploration. But, the State’s asbestos production was modest, apparently limited to two small amphibole asbestos operations-at a site near Lyman in Skagit County and a mine near Alta Lake in Okanogan County.
In 1891 (possibly earlier), an amphibole asbestos deposit near Lyman, in Skagit County (site number 41), was "uncovered for a distance of 75 feet, and at the cropping is said to be eight feet in width"; it was described as a "wonderful asbestos deposit" and "of excellent quality, the fibers, fine as silk, being in some instances as much as 18 inches in length" (Engineering and Mining Journal, 1891, p. 362). Engineering and Mining Journal (1896, p. 135) records that the first shipment comprised 75 tons and noted "there are now 15 horses employed packing from the mine to the [Skagit] river and from there it is hauled on a wagon to the railroad." The precise location of this asbestos deposit is vague, described simply as near "Hamilton" across the Skagit River from Lyman. The property reportedly included 11 claims (Glover, 1936). The asbestos of this deposit is described as amphibole asbestos of unspecified variety.
The geology of the deposit is also not reported. A geologic map (Tabor and others, 2003) of the area suggests the host rock is most likely greenschist.
Amphibole asbestos (unspecified type) was once mined from an open pit located about 1
mile from Alta Lake and 6 miles southwest of Pateros in Okanogan County (site number 37). Patty
and Glover (1921, p. 107-108) describe active mining and processing of this material that occurred
during 1921 by the Asbestomine Company: "This company grinds together short-fibred [sic]
amphibole and diatomaceous earth and the resultant product is the base for both a fireproof and a
cold water paint which they manufacture. Some of the material has also been made up into a
plaster." Their brief description of the deposit indicates that the amphibole forms massive lenses, in
part altered to talc, near the margins of granitic rocks. A geologic map (Gulick and Korosec, 1990)
of the area suggests that the host rock may be an altered amphibolite.
In northern Whatcom County, the Sumas Mountain landslide (site number 51) deposits
approximately 30,000 to 120,000 cubic yards of material annually into Swift Creek and the Sumas
The landslide material comprises ultramafic rock boulders and disaggregated and weathered
ultramafic rock, which each contain chrysotile. For several decades, landslide material has been
dredged from Swift Creek to reduce local flooding. Some of the chrysotile-bearing, dredged
materials have been used locally as fill material in construction projects, as road bedding, and other
purposes. The U.S. Environmental Protection Agency has been sampling and studying the dredged
landslide materials to evaluate the potential asbestos exposures to local residents and stakeholders
and to seek solutions for managing this active, asbestos-generating natural system (Wroble, 2009).
Although it was not specifically described as an asbestos producer, noteworthy is a quarry
that operated sometime in the 1930s on Burlington Hill, overlooking the town of Burlington in Skagit County (site number 56). According to Glover (1936, p. 14), "Asbestos-Talc Products of Washington, Inc., of Burlington, Skagit County, mines a somewhat fibrous soapstone-actinolite mixture that has developed in shear zones cutting greenstone. It is ground, mixed with asbestos and use [sic] for special cements."
The asbestos occurrences in Washington are not exclusively hosted by altered ultramafic
rocks. As examples, (1) “serpentine” asbestos at the California gold-silver mine (site number 35) is
hosted by metamorphosed volcanic rocks, and (2) chrysotile at the Coffin asbestos prospect (site
number 40) occurs in thin serpentine veins within marble, which formed from the contact
metamorphism of a dolomitic carbonate rock.
Fibrous Amphiboles in the Northwestern United States
During this study, several examples were noted in the geologic literature that mentioned the
presence of fibrous amphiboles in developed mineral deposits (such as metal mines and prospects) or
in undisturbed outcrops. These examples are shown on the map and described in a separate dataset
(fibrous_amphiboles.xls). Amphibole asbestos was not specifically mentioned in the descriptions of
these deposits. However, these sites indicate geologic settings with the potential to host asbestos.
The geologic settings for these examples of fibrous amphiboles are similar to those that elsewhere
form and host the reported asbestos. Thus, a discovery of asbestos in these areas would not be
unusual from a geologic standpoint. Also, the distinction between "fibrous" amphibole and
"regulatory" amphibole asbestos is often not clear-cut in natural amphibole-bearing deposits. The
regulatory criteria for the analyses of commercial-grade amphibole asbestos do not always apply
well to the natural occurrences of fibrous to asbestiform amphiboles; thus, these occurrences require
site-specific detailed microscopic analyses (Meeker and others, 2006).
The asbestos database (asbestos_sites.xls) summarizes information found in geologic
references examined by the author. The entries in the database are sorted by State and descending
order of latitude (north to south). Each asbestos site entry in the database includes these data fields:
Number used to identify the dataset entries with their corresponding locations on the map.
The State in which the reported asbestos occurrence, prospect, or mine occurs, using the
two-letter U.S. Postal Service abbreviation.
Site name as reported
The name of the former asbestos mine, former asbestos prospect, or reported occurrence,
matching the nomenclature used in the source literature.
This field indicates whether the asbestos site represents a former asbestos mine, former
prospect, or an occurrence. "Past producer" indicates that the deposit was mined and produced
asbestos ore for commercial uses sometime in the past.
"Past prospect" indicates that the asbestos deposit was once prospected (evaluated) for possible commercial use, typically by trenching and (or) drilling, but the deposit was not further developed. "Occurrence" indicates that asbestos was reported at this site. The occurrence category includes (1) sites where asbestos-bearing rock is described in a geologic map or report; and (2) asbestos noted as an accessory mineral or vein deposit within another type of mineral deposit.
The latitude of the site's location in decimal degrees, measured using the North American
Datum of 1927. The number of significant figures following the decimal point indicates the believed
accuracy of the location: (1) two significant figures (for example, 44.03) indicates an approximate
location based on a general description, (2) three significant figures (for example, 44.094) indicates a
fairly accurate location based on a detailed description or location shown on a small-scale map
(1:50,000 scale or smaller), and (3) four significant figures (for example, 42.5586) indicates a
precise location based on a detailed description or a location shown on a large-scale map (1:24,000
scale or larger).
Longitude was calculated in the same manner as latitude.
Asbestiform mineral(s) reported
This field identifies the type of asbestos present as described in the source literature.
Associated mineral(s) reported
Minerals mentioned in association with the asbestos, as they were described in the source
literature. The order in which each mineral is listed does not necessarily indicate its relative
abundance in the deposit, but rather its order of mention in the source report.
Host rock(s) reported
The host rock(s) for the asbestos is (are) listed when available as described in the source
52 OR Jackson Upper Applegate Creek 1 talc outcrops 42.7467 -123.0389 "***large boulders and pieces of float***contains abundant radiating fibrous amphibole" (Ferns and Ramp, 1988, p. 36). talc, serpentine metaserpentinite Ferns and Ramp (1988, p. 36)
53 OR Jackson Doe Peak 1 talc occurrence outcrops 42.0151 -122.7670 "A pale-green, foliated platy talc with minor and very finely disseminated magnetite***consists mostly of talc with trace amounts of chlorite and fibrous tremolite" (Ferns and Ramp, 1988, p. 35). talc, magnetite, chlorite serpentinite Ferns and Ramp (1988, p. 33, 35)
54 WA Stevens Van Stone mine historic lead-zinc mine 48.7606 -117.7564 "Tremolite occurs as radiating fibrous crystals up to 1 inch in length, generally colorless or, where intergrown with sphalerite, having a brown cast" (Cox, 1968, p. 1516-1517). jasperoid (silica), sphalerite, galena, brucite, calcite, palygorskite, pyrite, pyrrhotite, jamesonite, barite dolomite Cox (1968)
55 WA Chelan Golden Horn batholith outcrops 48.503 -120.667 "Single prismatic amphibole crystals are occasionally encountered with fibrous blue terminations resembling paint brushes or are totally covered with fibrous blue needles oriented parallel to the c-axis. According to analyses of the composite crystals, composition ranges from fluorine-rich riebeckite at the fibrous termination to ferrorichterite, then to riebeckite, ferrowinchite, ferrorichterite, and finally to katophorite at the base of the prism" (Becker, 1991, p. 457). numerous minerals reported--see Becker (1991) alkaline granite Boggs (1984); Becker (1991)
56 WA Skagit Burlington quarry quarry 48.4848 -122.3197 "Asbestos-Talc Products of Washington, Inc., of Burlington, Skagit County, mines a somewhat fibrous soapstone-actinolite mixture that has developed in shear zones cutting greenstone. It is ground, mixed with asbestos and use [sic] for special cements" (Glover, 1936, p. 14). talc, serpentine greenstone Glover (1936, p. 14); Bowles (1955, p. 28); Valentine (1960, p. 7)
57 WA Stevens Stranger Creek outcrops 48.407 -117.986 "Fibrous radiating tremolite interbedded with dolomite throughout a thickness of 1,000 ft" (Valentine, 1960, p. 8). not reported dolomite Valentine (1960, p. 8)
58 WA Stevens Boundary Butte prospect hole 48.000 -118.163 "Fibrous radiating tremolite occurs in a bed of altered dolomite 4 ft. thick" (Valentine, 1960, p. 8). not reported dolomite Valentine (1960, p. 8)
The references used to compile the site information are listed in this field. The full reference
citations are provided in the accompanying digital files References.pdf and References.xls.
Another database, fibrous_amphiboles.xls, lists seven localities where fibrous amphiboles
are described in the geologic literature. This database is organized in a manner similar to
asbestos_sites.xls with the exception of two data fields:
(1) The data field "Site type" replaces the data field "Development."
(2) The data field "Fibrous amphibole(s) description" replaces the data field "Asbestiform
mineral(s) reported." This field contains short excerpts of amphibole description, quoted directly
from the geologic literature.
Bowles, Oliver, 1955, The asbestos industry: U.S. Bureau of Mines Bulletin 552, 122 p.
Bright, J.H., and Ramp, Len, 1965, Oregon's asbestos potential: The Ore Bin, v. 27, no. 3, p.
Burragato, F., Comba, P., Baiocchi, V., Palladino, D.M., Simei, S., Gianfagna, A., Paoletti, L.,
and Pasetto, R., 2005, Geo-volcanological, mineralogical and environmental aspects of
quarry materials related to pleural neoplasm in the area of Biancavilla, Mount Etna (eastern
Sicily, Italy): Environmental Geology, v. 47, no. 6, p. 855-868.
Campbell, W.J., Blake, R.L., Brown, L.L., Cather, E.E., and Sjoberg, J.J., 1977, Selected silicate
minerals and their asbestiform varieties-Mineralogical definitions and
identification-characterization: U.S. Bureau of Mines Information Circular 8751, 56 p.
Churchill, R.K., and Hill, R.L., 2000, A general location guide for ultramafic rocks in
California-Areas more likely to contain naturally occurring asbestos: Sacramento, Calif.,
California Department of Conservation, Division of Mines and Geology, DMG Open-File
Report 2000-19. Available online at http://www.consrv.ca.gov/.
Clinkenbeard, J.P., Churchill, R.K., and Lee, Kiyoung, eds., 2002, Guidelines for geologic
investigations of naturally occurring asbestos in California: Sacramento, Calif., California
Department of Conservation, California Geological Survey Special Publication 124, 70 p.
Cossette, Marcel, 1984, Defining asbestos particulates for monitoring purposes, in Levadie,
Benjamin, ed., Definitions for asbestos and other health-related silicates: Philadelphia, Pa.,
American Society for Testing and Materials, ASTM Special Technical Publication 834, p.
Dodson, R.F., and Hammar, S.P., eds., 2006, Asbestos-Risk assessment, epidemiology, and
health effects: Boca Raton, Fla., Taylor & Francis Group, 425 p.
Engineering and Mining Journal, 1891, Washington, Ragit County: Engineering and Mining
Journal, v. 51, no. 12, (March 21, 1891), p. 362.
Engineering and Mining Journal, 1896, Washington, Skagit County: Engineering and Mining
Journal, v. 62, no. 6, (August 8, 1896), p. 135.
Fubini, Bice, and Fenoglio, Ivana, 2007, Toxic potential of mineral dusts: Elements, v. 3, p.
Gianfagna, A., Ballirano, P., Bellatreccia, F., Bruni, B., Paoletti, L., and Oberti, R., 2003,
Characterization of amphibole fibres linked to mesothelioma in the area of Biancavilla,
eastern Sicily, Italy: Mineralogical Magazine, v. 67, no. 6, p. 1221-1229.
Gulick, C.W., and Korosec, M.A., 1990, Geologic map of the Omak 1:100,000 quadrangle,
Washington: Washington Division of Geology and Earth Resources Open-File Report 90-12,
1 sheet, scale 1:100,000, includes 52 p. report.
Gianfagna, Antonio, and Oberti, Roberta, 2001, Fluoro-edenite from Biancavilla (Catania, Sicily,
Italy)-Crystal chemistry of a new amphibole end-member: American Mineralogist, v. 86, p.
Glover, S.L., 1936, Nonmetallic mineral resources of Washington: Washington Division of
Geology Bulletin No. 33, 135 p.
Guthrie, G.D., and Mossman, B.T., eds., 1993, Health effects of mineral dusts: Mineralogical
Society of America, Reviews in Mineralogy, v. 28, 584 p.
Horton, D.K., Bove, F., Kapil, V., 2008, Select mortality and cancer incidence among residents in
various U.S. communities that received asbestos-contaminated vermiculite ore from Libby,
Montana: Inhalation Toxicology, v. 20, issue 8, p. 767-775.
Krevor, S.C., Graves, C.R., Van Gosen, B.S., and McCafferty, A.E., 2009, Mapping the mineral
resource base for mineral carbon-dioxide sequestration in the conterminous United States:
U.S. Geological Survey Data Series 414, 14 p., 1 plate, and digital GIS shapefiles. Available
online at http://pubs.usgs.gov/ds/414/.
Levadie, Benjamin, ed., 1984, Definitions for asbestos and other health-related silicates:
Philadelphia, Pa., American Society for Testing and Materials, ASTM Special Technical
Publication 834, p. 1-147.
Meeker, G.P., Bern, A.M., Brownfield, I.K., Lowers, H.A., Sutley, S.J., Hoefen, T.M., and Vance,
J.S., 2003, The composition and morphology of amphiboles from the Rainy Creek Complex,
near Libby, Montana: American Mineralogist, v. 88, nos. 11-12, Part 2, p. 1955-1969.
Meeker, G.P., Lowers, H.A., Swayze, G.A., Van Gosen, B.S., Sutley, S.J., and Brownfield, I.K.,
2006, Mineralogy and morphology of amphiboles observed in soils and rocks in El Dorado
Hills, California: U.S. Geological Survey Open-File Report 2006-1362, 47 p. plus 4
appendixes. Available online at http://pubs.usgs.gov/of/2006/1362/.
Mossman, B.T., Bignon, J., Corn, M., Seaton, A., and Gee, J.B.L., 1990, Asbestos-Scientific
developments and implications for public policy: Science, v. 247, p. 294-301.
Nolan, R.P., Langer, A.M., Ross, M., Wicks, F.J., and Martin, R.F., eds., 2001, The health effects
of chrysotile asbestos-Contribution of science to risk-management decisions: The Canadian
Mineralogist, Special Publication 5, 304 p.
Occupational Safety and Health Administration, 1992, 29 CFR Parts 1910 and 1926 [Docket No.
H-033-d], Occupational exposure to asbestos, tremolite, anthophyllite and actinolite: Federal
Register, v. 57, no. 110, Monday, June 8, 1992, p. 24,310-24,331.
Patty, E.N., and Glover, S.L., 1921, The mineral resources of Washington with statistics for 1919:
Washington Geological Survey Bulletin No. 21, 155 p., 13 plates.
Peipins, L.A., Lewin, M., Campolucci, S., Lybarger, J.A., Miller, A., Middleton, D., Weis, C.,
Spence, M., Black, B., Kapil, V., 2003, Radiographic abnormalities and exposure to
asbestos-contaminated vermiculite in the community of Libby, Montana, U.S.A.:
Environmental Health Perspectives, v. 111, no. 14, p. 1753-1759.
Plumlee, G.S., and Ziegler, T.L., 2003, The medical geochemistry of dusts, soils, and other earth
materials, in Holland, H.D., and Turekian, K.K., eds., Treatise on geochemistry, volume
9-Environmental geochemistry: Amsterdam, Elsevier Pergamon, p. 263-310.
Ross, Malcolm, 1981, The geologic occurrences and health hazards of amphibole and serpentine
asbestos [chapter 6], in Veblen, D.R., ed., Amphiboles and other hydrous
pyriboles-Mineralogy: Mineralogical Society of America, Reviews in Mineralogy, v. 9A, p.
Ross, Malcolm, Kuntze, R.A., and Clifton, R.A., 1984, A definition for asbestos, in Levadie,
Benjamin, ed., Definitions for asbestos and other health-related silicates: Philadelphia, Pa.,
American Society for Testing and Materials, ASTM Special Technical Publication 834, p.
Ross, Malcolm, and Nolan, R.P., 2003, History of asbestos discovery and use and
asbestos-related disease in context with the occurrence of asbestos within ophiolite
complexes, in Dilek, Yildirim, and Newcomb, Sally, eds., Ophiolite concept and the
evolution of geological thought: Geological Society of America Special Paper 373, p.
Ross, Malcolm, and Virta, R.L., 2001, Occurrence, production and uses of asbestos, in Nolan,
R.P., Langer, A.M., Ross, Malcolm, Wicks, F.J., and Martin, R.F., eds., The health effects of
chrysotile asbestos-Contribution of science to risk-management decisions: The Canadian
Mineralogist, Special Publication 5, p. 79-88.
Skinner, H.C.W., Ross, Malcolm, and Frondel, Clifford, 1988, Asbestos and other fibrous
materials-Mineralogy, crystal chemistry, and health effects: New York, Oxford University
Press, 204 p.
Stanton, M.F., Layard, Maxwell, Tegeris, Andrew, Miller, Eliza, May, Margaret, Morgan,
Elizabeth, and Smith, Alroy, 1981, Relation of particle dimensions to carcinogenicity in
amphibole asbestoses and other fibrous minerals: Journal of the National Cancer Institute, v.
67, p. 965-975.
Sullivan, P.A., 2007, Vermiculite, respiratory disease, and asbestos exposure in Libby,
Montana—Update of a cohort mortality study: Environmental Health Perspectives, v. 115,
no. 4, p. 579-585.
Tabor, R.W., Haugerud, R.A., Hildreth, Wes, and Brown, E.H., 2003, Geologic map of the Mount
Baker 30- by 60-minute quadrangle, Washington: U.S. Geological Survey Geologic
Investigations Series Map I-2660, scale 1:100,000. Available online at
Tweedale, Geoffrey, and McCulloch, Jock, 2004, Chrysophiles versus chrysophobes-The white
asbestos controversy, 1950s-2004: Isis, v. 95, p. 239-259.
Van Gosen, B.S., 2005, Reported historic asbestos mines, historic asbestos prospects, and natural
asbestos occurrences in the Eastern United States: U.S. Geological Survey Open-File Report
2005-1189. Available online at http://pubs.usgs.gov/of/2005/1189/.
Van Gosen, B.S., 2006, Reported historic asbestos prospects and natural occurrences in the
Central United States: U.S. Geological Survey Open-File Report 2006-1211. Available
online at http://pubs.usgs.gov/of/2006/1211/.
Van Gosen, B.S., 2007a, Reported historic asbestos mines, historic asbestos prospects, and
natural asbestos occurrences in the Rocky Mountain States of the United States (Colorado,
Idaho, Montana, New Mexico, and Wyoming): U.S. Geological Survey Open-File Report
2007-1182. Available online at http://pubs.usgs.gov/of/2007/1182/.
Van Gosen, B.S., 2007b, The geology of asbestos in the United States and its practical
applications: Environmental & Engineering Geoscience, v. 13, no. 1, p. 55-68.
Van Gosen, B.S., 2008, Reported historic asbestos mines, historic asbestos prospects, and natural
asbestos occurrences in the Southwestern United States (Arizona, Nevada, and Utah): U.S.
Geological Survey Open-File Report 2008-1095. Available online at
van Oss, C.J., Naim, J.O., Costanzo, P.M., Giese, R.F., Jr., Wu, W., and Sorling, A.F., 1999,
Impact of different asbestos species and other mineral particles on pulmonary pathogenesis:
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GREGORY P. MEEKER
U.S. GEOLOGICAL SURVEY
U.S. DEPARTMENT OF THE INTERIOR
BEFORE THE COMMITTEE ON ENERGY AND COMMERCE
SUBCOMMITTEE ON ENVIRONMENT AND HAZARDOUS MATERIALS
U.S. HOUSE OF REPRESENTATIVES
FEBRUARY 28, 2008
Mr. Chairman and Members of the Subcommittee, thank you for the opportunity to present testimony on the mineralogy and geology of asbestos. My name is Greg Meeker and I am a geologist at the U.S. Geological Survey (USGS) in Denver, Colorado.
Many minerals found in nature grow in a form referred to as fibrous, that is, they possess physical properties similar to organic fibers. Asbestos is a term applied to a special group of fibrous silicate minerals that form as long, very thin fibers that usually occur in bundles. When handled or crushed, the asbestos bundles readily separate into individual mineral fibers. This type of mineral growth form or “habit” is called asbestiform (National Research Council, 1984; Skinner and others, 1988). The special properties of commercial-grade asbestos—long, thin, durable mineral fibers and fiber bundles with high tensile strength, flexibility, and resistance to heat, chemicals, and electricity—make it well suited for a number of commercial applications. This definition for asbestos is based on the properties that make it valuable as a commodity. When asbestos regulations were developed in the 1970’s it was these commercial fibers that were identified as most problematic from a health perspective because they were the most common species encountered in mining, processing, and manufacturing.
Although there are many asbestos minerals, some commercial and regulatory definitions of asbestos focus on chrysotile, the asbestiform member of the serpentine mineral group, and several members of the amphibole mineral group, including the asbestiform varieties of (1) riebeckite (commercially called crocidolite), (2) cummingtonite-grunerite (commercially called amosite), (3) anthophyllite (anthophyllite asbestos), (4) actinolite (actinolite asbestos), and (5) tremolite (tremolite asbestos). Other environmental statutes address asbestos more broadly, as other amphiboles are known to occur in the fibrous and/or asbestiform habit (Skinner and others, 1988) but have not been utilized commercially. These include, for example, winchite, richterite (Wylie and Huggins, 1980; Meeker and others, 2003), and fluoro-edenite (Gianfagna and Oberti, 2001; Gianfagna and others, 2003).
Asbestos Mineral Nomenclature
The academic mineralogy community has long classified minerals by name. This mineral nomenclature has evolved dramatically over the years and continues to evolve in response to advances in analytical technology and many other factors. The current academic nomenclature system for amphiboles is endorsed by the International Mineralogical Association (IMA) and recognizes approximately 70 distinct amphibole minerals (Leake and others, 1997). Under this world-recognized system, amphibole minerals are named based on their chemical composition and the exact chemical boundaries between different amphibole minerals are defined on the basis of various mineralogical or other considerations. It should also be noted that in most cases there is chemical gradation (called solid solution) between the different amphibole minerals. That is, there are rarely distinct natural chemical boundaries between the amphibole minerals, only arbitrary boundaries defined by the IMA.
Prior to 1978, amphiboles were primarily identified by optical properties using a transmitted light microscope. This optical identification led to ambiguities and multiple names in the technical literature for the same mineral. In 1978, the IMA’s Committee on Amphibole Nomenclature made the decision to redefine amphibole names on the basis of chemical composition and published a classification system that required the use of highly accurate chemical analyses (Leake and others, 1978), with the intent to help reduce these ambiguities. The current amphibole nomenclature established in 1997 is generally similar to the 1978 nomenclature, with the exception that chemical boundaries between several of the amphibole minerals were shifted. In addition to the formal 1978 and 1997 changes in amphibole nomenclature, further confusion results because common and commercial names for some asbestiform amphiboles are still used in some geological or commercial contexts; these include the names amosite, crocidolite, blue asbestos, brown asbestos, and white asbestos.
The "Libby, Montana amphibole" provides an excellent example of the difficulties that have arisen from the co-mingling of different amphibole nomenclatures. During the years that the Libby mine was active, geologists, miners, and regulators called the amphiboles tremolite, soda tremolite, sodium-rich tremolite, and, in one case, richterite. This terminology was used by the geologic and mineralogic communities, as well as by the health, regulatory, and industrial communities. The 1978 IMA change in nomenclature went largely unnoticed or was simply ignored outside of the community of academic mineralogists and geologists, and the Libby amphibole continued to be referred to as a sodium-rich variety of tremolite. Beginning in 2000, mineralogists began to reinvestigate the Libby amphibole and apply the current academic nomenclature, first identifying it as winchite (Wylie and Verkouteren, 2000) and later as winchite, richterite, and tremolite (Meeker and others, 2003). These findings have generated confusion in the asbestos community regarding the identification and nomenclature of the Libby amphibole and whether or not the material is regulated.
Some have taken the position that most of the Libby amphibole is primarily winchite and richterite and therefore is not currently regulated. However, if the nomenclature of Leake and others (1997) is the regulatory touchstone, then the following must also be true. Prior to 1978, all of the Libby asbestos (100 percent) would have been considered to be a form of tremolite and regulated based on the existing nomenclature at the time and the prescribed optical analysis methods for asbestos promulgated under National Emission Standards for Hazardous Air Pollutants (NESHAPs). Between 1978 and 1997 only 15 percent of the Libby asbestos would have been identified as tremolite based on the 1978 IMA system (Leake and others, 1978). Finally, after 1997, due to a mineralogically defined change in the IMA chemical boundaries (Leake and others, 1997), only 6 percent of the Libby asbestos would be classified as tremolite. There is no indication that the regulators intended different treatment for what remained the same underlying substance during this time period. Nonetheless, the Libby amphibole has historically been referred to as tremolite asbestos, and even today could be considered to be a form of tremolite asbestos under the guidelines established for standard Polarized Light Microscopy (PLM) asbestos analysis.
The example above illustrates a subtle but critical point, the Libby amphibole was not originally mistakenly identified as tremolite. The Libby amphibole was correctly identified prior to 1978 as a sodium-rich tremolite based on existing nomenclature and analytical methods. It was also correctly identified as primarily winchite and richterite, after application of the new academic nomenclature using more modern analytical methods. In this example, the IMA inadvertently redefined a regulated material for reasons totally unrelated to asbestos regulation.
Finally, it should be recognized that the nomenclature for amphiboles in the academic community will likely change again in the future (Hawthorne and Oberti, 2006) and new species of fibrous and asbestiform amphiboles may be identified.
Size and Shape of Asbestos Particles
The size and shape of asbestos particles can vary substantially within a single sample and from one sample to another, even if the mineral type is the same. Historically, most commercial asbestos used in products has been chrysotile (Virta and Mann, 1994). Chrysotile tends to have very thin fibers that are often very long and flexible prior to processing. Amphibole asbestos fibers, however, can display a large range of sizes from very long and thin to thick, relatively short, and brittle. A variety of sizes and shapes of amphibole asbestos fibers can occur together and can be inter-grown at the microscopic scale. In addition to the amphibole fibers that fit the commercial definition of asbestos, other amphibole particle types can also occur, again intermixed at the microscopic scale. These other particle types are often referred to by mineralogists as fibrous (non-asbestiform), acicular (needle-like) and prismatic (prism-like) (Meeker and others, 2006). Unfortunately, there are no distinct boundaries between these particle types - they often show a gradation from one to the next in the same sample or material. Also, there is considerable disagreement in the asbestos community about how to distinguish these particle types in a mixed sample and, more importantly, how these different particle types relate to toxicity. These issues were recently raised regarding naturally occurring asbestos in the community of El Dorado Hills California (EPA, 2008; Meeker and others, 2006).
Respirable fibers are those fibers small enough to penetrate into deep lung tissue. (Newman, 2001). Typically, not all fibers or asbestos particles in a material are of respirable size. A soil or aggregate sample containing 0.25 percent respirable amphibole fibers could contain more than 25,000,000 fibers per cubic centimeter. However, larger fiber bundles will continue to generate respirable fibers when disturbed. The degree to which respirable fibers could be liberated into the air by disturbance and become an inhalation hazard depends on many variables including the type of fiber or asbestos, the type of soil or aggregate, moisture content of the soil or aggregate, humidity of the air, and other factors. Therefore, any reliable determination of actual risk by direct measurement of the amount of fibers in the soil or aggregate would be extremely difficult.
Most amphibole minerals encountered in the majority of rock and soil types are not fibrous or asbestiform but occur as larger blocky or massive crystals. When these larger amphibole crystals are crushed or milled they break or "cleave" along specific directions that are related to the crystal structure of the particles. These particles are called cleavage fragments. Cleavage fragment particles are sometimes long and thin and are often difficult to distinguish from the other particle types discussed above.
In addition to the amphibole and chrysotile particles discussed above, other natural minerals exist that can occur as fibrous, or elongated, particles of respirable size. These elongated non-asbestos particles can be referred to as elongated mineral particles (EMP). One of these minerals, fibrous erionite, has been associated with very high rates of mesothelioma in Central Turkey (Baris, 1978). Fibrous erionite occurrences have been described in some places in the United States (Sheppard, 1996).
Geology of Asbestos
Geologists have documented that asbestos is formed only in specific and predictable geologic settings (Van Gosen, 2007a). The rocks that host asbestos minerals are consistently magnesium-rich (and often also iron-rich) rock types that have been altered in form and composition by metamorphic geologic processes; examples include altered ultramafic rocks and metamorphosed dolomite-rich rocks. In general, asbestos deposits are relatively rare and usually comprise a small volume of the total host rock body. The areas in which asbestos has formed are limited in extent in the United States. The USGS is conducting a study to map the locations of known sites of natural occurrences of asbestos in the United States (Van Gosen, 2005, 2006, 2007b). This work shows that asbestos deposits of various sizes are known to occur in at least 35 of the 50 States. The highest concentrations of asbestos deposits occur in: the eastern States, in a belt stretching from east-central Alabama to Vermont and Maine; the west-coast States of California, Oregon, and Washington; the upper Midwest, in Minnesota and Michigan; and an area of east-central Arizona. This work also shows that significant portions of the United States are not geologically likely to have substantial asbestos deposits.
In order to be of commercial value, asbestos must be in sufficient quality and purity for the intended application, and must occur in sufficient abundance to be mined at a profit. In nature, such occurrences are very rare. Far more common is material that can be present in small veins or pods and in quality that can grade from asbestiform to fibrous to acicular to prismatic. The asbestiform component of this material, when undisturbed by human activity, is often called "naturally occurring asbestos." As most commonly used, naturally occurring asbestos (NOA) refers to asbestos that occurs as a minor to major mineral component in some rocks, soils, sediments or waters as a result of natural geological processes. The term NOA can also apply to asbestos that has been transported by natural weathering and erosion processes from its original geologic source rock into air, soil, sediment or water. (Van Gosen, 2006). Not included in this definition would be commercially processed asbestos-containing materials, such as some insulation and fire protective materials in buildings or some types of automobile brake pads, in addition to soils, sediments, or waters contaminated by commercially-processed asbestos.
In addition, NOA should not include asbestos that occurs as impurities in other processed industrial minerals. For example, some products have been made using certain types of talc or vermiculite that contain amphibole asbestos as a natural contaminant (Van Gosen and others, 2004; EPA, 2008a).
Thank you for the opportunity to present this testimony. As a non-regulatory natural science agency, the USGS works closely with other Federal agencies and with non-Federal stakeholders to help answer many important questions regarding the nature of asbestos-related minerals, to develop new analytical methods and procedures for asbestos-related materials, to develop asbestos-related standard reference materials, and to provide important information about where asbestos-related minerals occur in the United States.
I am pleased to answer questions you might have.
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