Actinolite is a rare form of asbestos very similar to tremolite. In fact, their chemical formulas are the same except that actinolite has more iron than magnesium and the opposite is true for tremolite. The iron content in actinolite makes the crystal a green color, and the more iron, the darker the green. Actinolite consists of long, needle-like, thin elastic fibers, but it is more brittle and lacks the elasticity of chrysotile.
Like all forms of asbestos, asbestiform actinolite is a carcinogen that causes asbestos-related illnesses, including asbestosis and mesothelioma.
Zonolite Corporation, known for making vermiculite, uses actinolite in a number of its construction products, including thermal insulation, fireproofing, concrete aggregates, and vermiculite for plants. Other products that may contain actinolite include drywall compounds, joint compounds, and children’s toys.
Significant problems with asbestiform actinolite like other forms of asbestos, asbestiform actinolite breaks easily, releasing dust that contains fibers, which can be inhaled.
A 2002 incident in New Jersey’s Meadowlands involved the dumping of 30,000 cubic yards of rock that contained actinolite asbestos. The rock had much higher levels of actinolite than previously thought. The rocks contained up to 10 percent actinolite asbestos, far exceeding accepted safety standards. The drilling, blasting, and excavating that released asbestos dust into the air created a considerable concern in the area. Because of the mesothelioma latency period, it may be decades before anyone can measure the effect that the airborne actinolite asbestos.