Winstanleyite is an extremely rare tellurite mineral discovered primarily in the oxidized zone of the Moctezuma tellurium mine in Mexico. It typically appears as small, vibrant yellow, transparent cubic or tetrahedral crystals nestled within cavities of altered volcanic rock.
Is this winstanleyite?
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 winstanleyite with a known reference. Winstanleyite sits at Mohs 3-4 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Winstanleyite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Winstanleyite typically shows a adamantine luster.
- 4Match the color rangeCompare against the expected color range: yellow, yellowish-brown.
- 5Look at form & habitCrystal system: cubic. Typical habit: equant crystals, tetrahedrons.
Often confused with
Winstanleyite vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Streak differs — Winstanleyite leaves white, Spiridonovite leaves black; luster reads adamantine on Winstanleyite and metallic on Spiridonovite.
How to tell apart: Tegengrenite is the harder of the two (Mohs 6 vs. 3-4); streak differs — Winstanleyite leaves white, Tegengrenite leaves black; luster reads adamantine on Winstanleyite and metallic on Tegengrenite.
Often found alongside winstanleyite
Minerals reported to co-occur with winstanleyite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- TiTe₃O₈
- Mohs hardness
- 3-4
- Density
- 7.3 g/cm³
- Colors
- Streak
- White
- Luster
- Adamantine
- Transparency
- Transparent
- Crystal system
- Cubic
- Crystal habit
- Equant Crystals, Tetrahedrons
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Hydrothermal Veins in Rhyolite
- Typical price
- $50-300 per specimen
Where rockhounds find winstanleyite
Classic worldwide localities
- Moctezuma mine, Sonora, Mexico
Field-hunting tip
Look in hydrothermal veins in rhyolite country — that is the host setting where winstanleyite typically forms. If you start seeing paratellurite, emplectite, quetzalcoatlite in float, you are in the right ground. Field specimens usually show a equant crystals, tetrahedrons habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find winstanleyite on the map
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