Donwilhelmsite is a rare high-pressure mineral discovered in lunar meteorites that formed during impact events on the Moon. It is a structural polymorph of anorthite and typically occurs as microscopic inclusions within impact-melted breccias.
Is this donwilhelmsite?
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 donwilhelmsite with a known reference. Donwilhelmsite sits at Mohs not determined, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Donwilhelmsite leaves a not determined streak.
- 3Read the lusterHold the specimen under a strong light. Donwilhelmsite typically shows a metallic luster.
- 4Match the color rangeCompare against the expected color range: dark brown, black.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: anhedral grains.
Often confused with
Donwilhelmsite vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside donwilhelmsite
Minerals reported to co-occur with donwilhelmsite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- CaAl₂Si₂O₈
- Mohs hardness
- not determined
- Density
- 4.15 g/cm³
- Colors
- Streak
- Not Determined
- Luster
- Metallic
- Transparency
- Opaque
- Crystal system
- Monoclinic
- Crystal habit
- Anhedral Grains
- Cleavage
- Not Determined
- Rarity
- Rare
- Uses
- Scientific Research
- Host rock
- Lunar Impact Melt
Where rockhounds find donwilhelmsite
Classic worldwide localities
- Dhofar 025 meteorite
- Lunar meteorites
Field-hunting tip
Look in lunar impact melt country, the host setting where donwilhelmsite typically forms. If you start seeing olivine, pyroxene, maskelynite in float, you are in the right ground. Field specimens usually show a anhedral grains habit, so train your eye for that shape before scanning the outcrop.
Common questions
How do you identify donwilhelmsite?+
Where is donwilhelmsite found?+
What rocks look like donwilhelmsite?+
What minerals are found with donwilhelmsite?+
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What is donwilhelmsite used for?+
Find donwilhelmsite on the map
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