Tremolite (Ca₂Mg₅Si₈O₂₂(OH)₂) is the magnesium end-member of the calcic amphibole group and the principal mineral of nephrite jade. It forms in metamorphosed dolomitic carbonates as long fibrous to bladed crystals — the same Tremolite that constitutes the nephrite of Hetian (Xinjiang) and the historic European jade trade. Pure Tremolite is white to pale gray; iron substitution darkens it toward Actinolite.
Key Facts
- Mohs hardness 5–6.
- Monoclinic amphibole; ~120° / 60° prismatic cleavage angles (vs. pyroxene’s ~87°).
- Forms continuous solid-solution with actinolite (Fe-bearing) and ferro-actinolite.
- Fibrous Tremolite was once mined as asbestos.
- Compact aggregates form nephrite jade — toughness exceeds discrete crystal hardness.
Notable Localities
Mt. Greiner (Zillertal, Austria) is the type-locality. Hetian (Xinjiang) and Manas (Xinjiang) supply nephrite jade.
Found at these Localities
- Tunaberg (图纳贝里钴矿(瑞典))
- Hetian (Khotan) Jade District (和田玉矿区)
