Stokesite is a rare calcium tin silicate that typically forms as small, colorless, prismatic crystals. It is primarily prized by advanced mineral collectors and is most famously associated with granite pegmatite deposits where it occurs as a secondary mineral in vugs.
Is this stokesite?
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 stokesite with a known reference. Stokesite sits at Mohs 6 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Stokesite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Stokesite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: colorless, white.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: prismatic crystals.
Often confused with
Stokesite vs. its common look-alikes — and how to tell them apart in the field.
Often found alongside stokesite
Minerals reported to co-occur with stokesite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- CaSnSi₃O₉·2H₂O
- Mohs hardness
- 6
- Density
- 2.98 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Orthorhombic
- Crystal habit
- Prismatic Crystals
- Cleavage
- Distinct On {101}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Granite Pegmatites
- Typical price
- $50-300 per specimen
Where rockhounds find stokesite
Classic worldwide localities
- Cornwall, England
- San Diego County, California
- Pieskowa Skala, Poland
Field-hunting tip
Look in granite pegmatites country — that is the host setting where stokesite typically forms. If you start seeing axinite, cassiterite, fluorite in float, you are in the right ground. Field specimens usually show a prismatic crystals habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find stokesite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
