Diaspore is an aluminum oxide hydroxide mineral known for its excellent cleavage and occasional color-changing properties in gem-grade material. It typically forms as platy or acicular crystals within bauxite-rich metamorphic rocks or hydrothermal veins. Collectors prize it for its high luster and the distinct pleochroism exhibited by transparent specimens.
Is this diaspore?
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 diaspore with a known reference. Diaspore sits at Mohs 6.5-7 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Diaspore leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Diaspore typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: white, gray, colorless, yellowish, brownish, violet, greenish.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: platy or needle-like crystals, foliated masses, or massive scales.
Often confused with
Diaspore vs. its common look-alikes — and how to tell them apart in the field.
Often found alongside diaspore
Minerals reported to co-occur with diaspore. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- AlO(OH)
- Mohs hardness
- 6.5-7
- Density
- 3.3-3.5 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Orthorhombic
- Crystal habit
- Platy or Needle-like Crystals, Foliated Masses, Or Massive Scales
- Cleavage
- Perfect in One Direction
- Rarity
- Uncommon
- Uses
- Gemstone, Collector, Industrial
- Host rock
- Metamorphic Bauxite Deposits, Emery Deposits, And Some Pegmatites
- Typical price
- $20-100 per gram for gem-grade material, $10-50 for mineral specimens
Where rockhounds find diaspore
1 mapped spotsClassic worldwide localities
- Mugla, Turkey
- Ural Mountains, Russia
- Chester, Massachusetts, USA
- Postmasburg, South Africa
- Kremnica, Slovakia
Field-hunting tip
Look in metamorphic bauxite deposits, emery deposits, and some pegmatites country — that is the host setting where diaspore typically forms. If you start seeing corundum, chlorite, magnetite in float, you are in the right ground. Field specimens usually show a platy or needle-like crystals, foliated masses, or massive scales habit, so train your eye for that shape before scanning the outcrop. In the U.S., the densest reported localities are in Massachusetts — start trip planning there.
Common questions
How do you identify diaspore?+
Where is diaspore found?+
Can I find diaspore in the United States?+
How much is diaspore worth?+
What rocks look like diaspore?+
What minerals are found with diaspore?+
What kind of rock does diaspore form in?+
What is diaspore used for?+
Find diaspore on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
