Osumilite-(Mg) is a rare cyclosilicate that often forms short, hexagonal prismatic crystals reminiscent of beryl. It is primarily found in high-grade metamorphic rocks and specific volcanic environments, often occurring as inclusions or tiny crystals within larger mineral matrices. Collectors prize it for its rarity and its clear, sometimes pale-blue crystalline appearance.
Is this osumilite-(mg)?
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 osumilite-(mg) with a known reference. Osumilite-(Mg) sits at Mohs 7 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Osumilite-(Mg) leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Osumilite-(Mg) typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: colorless, pale blue, blue-gray.
- 5Look at form & habitCrystal system: hexagonal. Typical habit: prismatic crystals, anhedral grains.
Often confused with
Osumilite-(Mg) vs. its common look-alikes — and how to tell them apart in the field.
Often found alongside osumilite-(mg)
Minerals reported to co-occur with osumilite-(mg). Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- (K,Na)(Mg,Fe)₂Al₃(Si,Al)₁₂O₃₀
- Mohs hardness
- 7
- Density
- 2.65 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Hexagonal
- Crystal habit
- Prismatic Crystals, Anhedral Grains
- Cleavage
- Poor
- Rarity
- Rare
- Uses
- Collector
- Host rock
- High-grade Metamorphic Rocks and Volcanic Rocks
- Typical price
- $20-100 for small, well-defined crystals
Where rockhounds find osumilite-(mg)
Classic worldwide localities
- Japan
- Italy
- Germany
- France
- Antarctica
Field-hunting tip
Look in high-grade metamorphic rocks and volcanic rocks country — that is the host setting where osumilite-(mg) typically forms. If you start seeing quartz, orthoclase, biotite 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 osumilite-(mg)?+
Where is osumilite-(mg) found?+
How much is osumilite-(mg) worth?+
What rocks look like osumilite-(mg)?+
What minerals are found with osumilite-(mg)?+
What kind of rock does osumilite-(mg) form in?+
What is osumilite-(mg) used for?+
Find osumilite-(mg) on the map
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