Tremolite

Crystal system · Monoclinic

Tremolite is a silicate mineral prized by collectors for its exceptional color range, with several world-class Chinese localities.

About Tremoliteextended article

China-iconic

China is a defining locality for Tremolite · 透闪石. See the Chinese collector page →

Save to favoritesview your list
Elemental Composition (by mass)
ElementMass %Visual
O Oxygen45.10%
Si Silicon28.79%
Mg Magnesium15.57%
Ca Calcium10.27%
H Hydrogen0.26%
Computed from simplified end-member formula. Solid-solution series, water content, and trace substitutions cause real-world variation.
IMA Abbreviation (Whitney-Evans 2010)
Tr
→ Tremolite
Ca-Mg amphibole
Standard symbol from American Mineralogist (Whitney & Evans, 2010). Used in thin-section labeling, phase diagrams, and IMA-style species records.
Pronunciation
/ˈtrɛməlaɪt/
TREM-uh-lite
from Tremola Valley
⚠ Safety & Handling
asbestiformhigh (some)
Some habits asbestiform.
Handling: Avoid fibrous specimens. Solid bladed crystals are safe.
Information provided in good faith. Consult local hazmat regulations for transport and disposal. Severely hazardous specimens may require special storage cabinets.
Type Locality
Tremola, Val Leventina — Switzerland
Described 1789 by Saussure
Cleavage & Fracture
Cleavage:
perfect 2 directions ~56°/124°
Fracture:
splintery
Asbestiform varieties can split fibrously.
Collector tier: Micromount / Niche
Best appreciated at thumbnail or smaller scale — often dull-colored, sub-millimeter, or radioactive. Specialist appeal.
Mohs 5–6
Vickers (~) 540 HV
Knoop (~) 620 HK
Geological setting
Metamorphic
Element composition by mass

Formula: Ca₂Mg₅Si₈O₂₂(OH)₂ · molar mass: 812.35 g/mol

O 47.27%
Si 27.66%
Mg 14.96%
Ca 9.87%
H 0.25%

Computed from atomic weights (IUPAC 2021). Site-occupancy groups (Fe,Mn) split equally.

GroupAmphibole Group
Related members: Hornblende · Actinolite
Mohs Hardness 5–6

Tremolite sits at 5–6 on the Mohs scale — just hard enough to scratch glass.

🔊 Read aloud
Colors:
Streak
White
Crystal system
Monoclinic
✓ I have this★ WishlistView my collection →

📇 Print ID card

SilicatesSilicates (Inosilicates — Amphiboles)
TL;DR · 1 min read
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.
Text size:AAA

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.

More minerals to explore #

Identification & care

Crystals commonly develop as bladed, prismatic crystals; fibrous (asbestiform); massive, granular; radiating and columnar aggregates. Its color range is broad, including white, colorless, pale green, pale grey, pale yellow, and fibrous variety = white asbestos. The luster is vitreous, silky (fibrous), pearly, the streak is white, and specimens range from transparent to translucent. The cleavage is perfect on {110}, two directions at ~56° and 124° (characteristic amphibole cleavage). The fracture is uneven, splintery (fibrous), which aids identification.

Collector context

How it forms

Tremolite forms in metamorphosed dolomitic limestones (in marbles and calc-silicate rocks); also in ultramafic/ophiolitic rocks; hydrothermal veins in mafic rocks. It is commonly found in association with dolomite, calcite, diopside, talc, phlogopite, chlorite, forsterite.

Classic Chinese localities

Documented Chinese occurrences are recorded at Shangbao Mine, Jiama Cu-polymetallic deposit and Xianghualing Sn-polymetallic ore field, among others.

Why collectors care

Collectors pursue Tremolite for the clarity of its crystal form and, in good material, saturated color that reads instantly across a display case. A well-terminated tremolite on clean matrix photographs well, identifies quickly, and anchors a cabinet piece. Top Chinese specimens over the last two decades have reset the bar for what tremolite looks like at collector grade.

What affects value

Value in Tremolite is assessed, in typical order of weight, against: (1) locality provenance; (2) size relative to the species norm; (3) crystal form and termination sharpness; (4) color saturation and zoning; (5) transparency and internal clarity; (6) matrix quality and aesthetic balance; (7) condition (absence of damage, chips, or repair). Cleaning quality and verified locality documentation act as multipliers across the above.

Naming history

The name Tremolite has a specific etymological and historical context — see Mindat's reference entry for provenance details. We have retained naming data at the record level; published prose is paraphrased from factual fields rather than copied from source.