Non-Asbestiform

Non-asbestiform describes a mineral that has the same chemistry as an asbestos mineral but grew in an ordinary crystal shape (blocky, prismatic or columnar) rather than as fine, flexible fibers. Crushing non-asbestiform minerals produces cleavage fragments, some of which are long and thin enough to look like fibers.

Origin

Mineralogists distinguish a mineral's species (its chemistry and structure) from its habit (the shape in which it grows). The term came into regulatory use in the 1970s and 1980s, when mining interests argued that crushed non-asbestiform tremolite, actinolite and anthophyllite should not be regulated as asbestos. OSHA agreed in 1992 and removed the non-asbestiform forms of those minerals from its asbestos standards.

Significance in Asbestos Context

Defendants in talc, taconite, vermiculite and stone cases often argue that the amphibole particles found in a product or in lung tissue were non-asbestiform cleavage fragments rather than asbestos. Plaintiffs' experts respond that the health hazard depends on the size and shape of the particles that are breathed in, not on how the parent crystal grew, and that many products contain both forms. The distinction is made under the microscope from features such as fiber bundles, splayed ends, curvature and the width distribution of the particles.

Example Sentence

The defense mineralogist testified that the tremolite in the talc was non-asbestiform and broke into cleavage fragments, while the plaintiff's expert counted bundles with splayed ends typical of asbestiform fibers.

Related Terms

Asbestiform, Habit, Cleavage Fragment, Fibrous Habit, Tremolite, Elongate Mineral Particles (EMPs), Regulated Asbestos

Notes

• In talc and mineral cases, expect this argument; ask whether your experts have examined the actual particles under TEM.
• Preserve product samples, packaging and any test reports; the habit argument turns on physical evidence.