Fluoro-tremolite is a fluorine-dominant member of the amphibole group, forming elongated prismatic or fibrous crystals. It is most frequently encountered in contact metamorphosed limestones and dolomites, often occurring as white to pale green sprays.

Hardness

5-6

Mohs

Luster

Vitreous

Streak

White

Transparency

Translucent

mineraluncommonAmphibole Group family

Fluoro-tremolite

Hardness: 5-6
Luster: Vitreous
Streak: White
Transparency: Translucent

Is this fluoro-tremolite?

5-step field check

Run through these checks against the specimen in your hand. The more boxes tick, the more confident the ID.

1
Test the hardness
Try to scratch fluoro-tremolite with a known reference. Fluoro-tremolite sits at Mohs 5-6 — softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Fluoro-tremolite leaves a white streak.
3
Read the luster
Hold the specimen under a strong light. Fluoro-tremolite typically shows a vitreous luster.
4
Match the color range
Compare against the expected color range: white, colorless, pale green, gray.
5
Look at form & habit
Crystal system: monoclinic. Typical habit: bladed, prismatic, fibrous.

Often confused with

Fluoro-tremolite vs. its common look-alikes — and how to tell them apart in the field.

mineral

Actinolite

Mohs 5.5-6

How to tell apart: Luster reads vitreous on Fluoro-tremolite and vitreous to silky on Actinolite.

Often found alongside fluoro-tremolite

Minerals reported to co-occur with fluoro-tremolite. Spotting these in float or country rock is a strong cue you are in the right ground.

All properties

Chemical formula: Ca₂Mg₅Si₈O₂₂(F,OH)₂
Mohs hardness: 5-6
Density: 2.9-3.0 g/cm³
Colors: White Colorless Pale Green Gray
Streak: White
Luster: Vitreous
Transparency: Translucent
Crystal system: Monoclinic
Crystal habit: Bladed, Prismatic, Fibrous
Cleavage: Perfect Prismatic
Rarity: Uncommon
Uses: Collector, Mineralogical Study
Host rock: Metamorphic Carbonate Rocks
Typical price: $10-100 thumbnail to cabinet specimen

Where rockhounds find fluoro-tremolite

Classic worldwide localities

Italy
USA
Canada
Switzerland

Field-hunting tip

Look in metamorphic carbonate rocks country — that is the host setting where fluoro-tremolite typically forms. If you start seeing calcite, diopside, forsterite in float, you are in the right ground. Field specimens usually show a bladed, prismatic, fibrous habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify fluoro-tremolite?+

Mohs hardness is 5-6. It typically shows a vitreous luster. The streak is white. Common colors include white, colorless, pale green, gray.

Where is fluoro-tremolite found?+

Notable localities include Italy; USA; Canada; Switzerland.

How much is fluoro-tremolite worth?+

Typical asking prices fall in the range of $10-100 thumbnail to cabinet specimen. Quality, size, and provenance can move individual specimens well outside that range.

Is fluoro-tremolite safe to handle?+

It contains toxic constituents. Asbestiform varieties may contain fine, inhalable fibers that pose long-term respiratory hazards; avoid grinding or crushing and handle with care. Handle with care, avoid grinding or breathing dust, and store separately.

What rocks look like fluoro-tremolite?+

Fluoro-tremolite is most often confused with Actinolite, Tremolite, Wollastonite. A quick hardness test and a streak check separate the look-alikes faster than color alone.

What minerals are found with fluoro-tremolite?+

Fluoro-tremolite commonly co-occurs with Calcite, Diopside, Forsterite, Talc. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does fluoro-tremolite form in?+

Fluoro-tremolite typically forms in metamorphic carbonate rocks. Working float back to the host body is the standard way to chase a fresh occurrence.

What is fluoro-tremolite used for?+

Fluoro-tremolite is used in collector, mineralogical study.

Find fluoro-tremolite on the map

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