Grossmanite is an extremely rare titanium-rich pyroxene found almost exclusively in calcium-aluminum-rich inclusions within carbonaceous chondrite meteorites. It appears as dark green to black massive grains and is highly sought after by meteorite collectors and mineralogists studying the early formation of the solar system.

Hardness

6-7

Mohs

Luster

Vitreous

Streak

White

Transparency

Translucent

mineralrarePyroxene Group family

Grossmanite

Hardness: 6-7
Luster: Vitreous
Streak: White
Transparency: Translucent

No image

Is this grossmanite?

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 grossmanite with a known reference. Grossmanite sits at Mohs 6-7 — softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Grossmanite leaves a white streak.
3
Read the luster
Hold the specimen under a strong light. Grossmanite typically shows a vitreous luster.
4
Match the color range
Compare against the expected color range: dark green, black.
5
Look at form & habit
Crystal system: monoclinic. Typical habit: massive.

Often confused with

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

Often found alongside grossmanite

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

All properties

Chemical formula: CaTiAl₂O₆
Mohs hardness: 6-7
Density: 3.3-3.4 g/cm³
Colors: Dark Green Black
Streak: White
Luster: Vitreous
Transparency: Translucent
Crystal system: Monoclinic
Crystal habit: Massive
Cleavage: Good in Two Directions
Rarity: Rare
Uses: Collector, Research
Host rock: Calcium-aluminum-rich Inclusions in Carbonaceous Chondrite Meteorites
Typical price: $100-500+ depending on meteorite provenance

Where rockhounds find grossmanite

Classic worldwide localities

Allende Meteorite (Mexico)

Field-hunting tip

Look in calcium-aluminum-rich inclusions in carbonaceous chondrite meteorites country — that is the host setting where grossmanite typically forms. If you start seeing melilite, spinel, perovskite in float, you are in the right ground. Field specimens usually show a massive habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify grossmanite?+

Mohs hardness is 6-7. It typically shows a vitreous luster. The streak is white. Common colors include dark green, black.

Where is grossmanite found?+

Notable localities include Allende Meteorite (Mexico).

How much is grossmanite worth?+

Typical asking prices fall in the range of $100-500+ depending on meteorite provenance. Quality, size, and provenance can move individual specimens well outside that range.

What rocks look like grossmanite?+

Grossmanite is most often confused with Diopside, Esseneite. A quick hardness test and a streak check separate the look-alikes faster than color alone.

What minerals are found with grossmanite?+

Grossmanite commonly co-occurs with Melilite, Spinel, Perovskite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does grossmanite form in?+

Grossmanite typically forms in calcium-aluminum-rich inclusions in carbonaceous chondrite meteorites. Working float back to the host body is the standard way to chase a fresh occurrence.

What is grossmanite used for?+

Grossmanite is used in collector, research.

Find grossmanite on the map

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