Tremolite (Dimensions: 1" across. Entire specimen 4" x 1.5" x 1") Locality: Balmat, Balmat-Edwards Zinc District, St. Lawrence County, New York, USA Original de — Photo: John Krygier · Public domain
Tremolite
Also known as: Nephrite jade (with actinolite), Hexagonite (pink var.).
A calcium-magnesium amphibole — the creamy-white mineral whose fibrous form is regulated as asbestos.
Intro adapted from Wikipedia (CC BY-SA).
Tremolite is an IMA-recognized mineral species in the silicate class, with the chemical formula Ca₂(Mg₅.₀₋₄.₅Fe²⁺₀.₀₋₀.₅)Si₈O₂₂(OH)₂.
It crystallizes in the monoclinic crystal system (space group C2/m). It is a member of the Amphibole structural group.
Key properties: Mohs hardness 5–6; specific gravity 2.99–3.03; typically white or colorless or gray or green; white streak; Vitreous luster; refractive index 1.619; optically biaxial.
IMA symbol Tr, IMA status: approved, named in 1789.
From contact metamorphism of Ca-Mg siliceous sediments; in greenschist facies metamorphics derived from ultramafic or magnesium carbonate rocks.
It is found associated with Calcite, dolomite, calcian garnet, wollastonite, talc, diopside, forsterite, cummingtonite, magnesio-cummingtonite, riebeckite, winchite.
The name refers to an occurrence in the Tremola Valley, southern St. Gotthard Mountains, Switzerland. All rights reserved. No par t of t his publication may b e reproduced.
Collections: Everyday Minerals, Collector Favorites.