Kushiroite is a very rare calcium-aluminum pyroxene that was first identified in terrestrial rocks from the Kushiro region of Japan. It is typically found as small, dark-colored grains in high-temperature metamorphic environments or in certain chondritic meteorites.

Hardness

6-7

Mohs

Luster

Vitreous

Streak

White

Transparency

Translucent

mineralrarePyroxene Group family

Kushiroite

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

No image

Is this kushiroite?

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 kushiroite with a known reference. Kushiroite 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. Kushiroite leaves a white streak.
3
Read the luster
Hold the specimen under a strong light. Kushiroite typically shows a vitreous luster.
4
Match the color range
Compare against the expected color range: green, dark green, black, brownish.
5
Look at form & habit
Crystal system: monoclinic. Typical habit: prismatic crystals, anhedral grains.

Often confused with

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

How to tell apart: Streak differs, so Kushiroite leaves white, Hedenbergite leaves white to pale green; luster reads vitreous on Kushiroite and vitreous to resinous on Hedenbergite.

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Often found alongside kushiroite

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

All properties

Chemical formula: CaAlAlSiO₆
Mohs hardness: 6-7
Density: 3.5-3.6 g/cm³
Colors: Green Dark Green Black Brownish
Streak: White
Luster: Vitreous
Transparency: Translucent
Crystal system: Monoclinic
Crystal habit: Prismatic Crystals, Anhedral Grains
Cleavage: Good in Two Directions
Rarity: Rare
Uses: Collector
Host rock: Metamorphic Rocks, Meteorites
Typical price: $50-500 depending on specimen size

Where rockhounds find kushiroite

Classic worldwide localities

Kushiro, Hokkaido, Japan
various meteorite impact sites

Field-hunting tip

Look in metamorphic rocks, meteorites country, the host setting where kushiroite typically forms. If you start seeing olivine, plagioclase, spinel in float, you are in the right ground. Field specimens usually show a prismatic crystals, anhedral grains habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify kushiroite?+

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

Where is kushiroite found?+

Notable localities include Kushiro, Hokkaido, Japan; various meteorite impact sites.

How much is kushiroite worth?+

Typical asking prices fall in the range of $50-500 depending on specimen size. Quality, size, and provenance can move individual specimens well outside that range.

What rocks look like kushiroite?+

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

What minerals are found with kushiroite?+

Kushiroite commonly co-occurs with Olivine, Plagioclase, Spinel. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does kushiroite form in?+

Kushiroite typically forms in metamorphic rocks, meteorites. Working float back to the host body is the standard way to chase a fresh occurrence.

What is kushiroite used for?+

Kushiroite is used in collector.

Find kushiroite on the map

RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.