Diopside is a common rock-forming pyroxene mineral that frequently appears in contact-metamorphosed limestones. Collectors look for its characteristic prismatic, often square-sectioned crystals and distinctive green hues, with the deep 'chrome-diopside' variety being especially prized for its vivid color.
Is this diopside?
5-step field checkRun through these checks against the specimen in your hand. The more boxes tick, the more confident the ID.
- 1Test the hardnessTry to scratch diopside with a known reference. Diopside sits at Mohs 5.5-6.5, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: white, gray, gray-green.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous or dull.
- 4Match the color rangeCompare against the expected color range: white, gray, green, yellow-green, dark green, black, blue, brown, colorless.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: blocky, granular, prismatic.
Often confused with
Diopside vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside diopside
Minerals reported to co-occur with diopside. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- CaMgSi₂O₆
- Mohs hardness
- 5.5-6.5
- Density
- 3.22-3.38 g/cm³
- Streak
- White, gray, gray-green
- Luster
- Vitreous or dull
- Transparency
- Transparent to opaque
- Crystal system
- Monoclinic
- Crystal habit
- Blocky, granular, prismatic
- Cleavage
- Distinct on {110}, (110) ^ (110) ~87°; partings on {100} and probably {010}
- Fluorescence
- Fluorescent
- Rarity
- Common
- Uses
- Collector, Gemstone, Lapidary
- Host rock
- Typical of metamorphosed siliceous Ca, Mg-rich rocks of the pyroxene-hornfels or epidote-amphibolite facies; common in skarns, Ca, Mg-rich gneisses and schists, and some kimberlites and peridotites
Where rockhounds find diopside
29 mapped spotsClassic worldwide localities
- DeKalb, St. Lawrence Co., Natural Bridge, Jefferson Co., Sing Sing, near Ossining, Westchester Co., New York, USA
- Ducktown, Polk Co., Tennessee, USA
- Schwarzenstein, Zillertal, and near Prägraten, Tirol, Austria
- Ala, Piedmont, and St. Marcel, Val d'Aosta, Italy
- Otokumpu, Finland
- Akhmatovsk deposit, near Zlatoust, Ural Mountains, Russia
U.S. states with diopside
Each link opens a state-specific list of mapped rockhounding spots that produce diopside.
Field-hunting tip
Where it forms: Typical of metamorphosed siliceous Ca, Mg-rich rocks of the pyroxene-hornfels or epidote-amphibolite facies; common in skarns, Ca, Mg-rich gneisses and schists, and some kimberlites and peridotites. If you start seeing calcite, forsterite, chondrodite in float, you are in the right ground. Typical habit: blocky, granular, prismatic. Train your eye for that shape before scanning the outcrop. In the U.S., the densest reported localities are in Utah, New York, Vermont. Start trip planning there.
More diopside photos
Common questions
How do you identify diopside?+
Where is diopside found?+
Can I find diopside in the United States?+
What rocks look like diopside?+
What minerals are found with diopside?+
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Find diopside on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
