bostonite

from The Century Dictionary.

• noun A trade-name for Canadian asbestos, a variety of chrysotile or fibrous serpentine.
• noun In petrography, a term proposed by Rosenbuseh (1882) for certain fine-grained igneous rocks of the syenite family, consisting chiefly of alkali feldspars (microcline, mierocline-microperthite, anorthoclase or orthoclase).