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 4, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: very pale yellow.
- 3Read the lusterHold the specimen under a strong light. Luster: adamantine.
- 4Match the color rangeCompare against the expected color range: yellow, light brown.
- 5Look at form & habitCrystal system: cubic. Typical habit: cubic crystals, octahedral crystals.
Often confused with
Winstanleyite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Winstanleyite leaves very pale yellow, 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. 4); luster reads adamantine on Winstanleyite and sub-adamantine 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
- 4
- Density
- 5.57 g/cm³
- Colors
- Streak
- Very pale yellow
- Luster
- Adamantine
- Transparency
- Semitransparent
- Crystal system
- Cubic
- Crystal habit
- Cubic crystals, octahedral crystals
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Very rare in strongly altered and pyritized granodiorite from the dump of a hydrothermal Au–Te-bearing ore deposit
Where rockhounds find winstanleyite
Classic worldwide localities
- Grand Central mine, Tombstone, Cochise Co., Arizona, USA
Field-hunting tip
Where it forms: Very rare in strongly altered and pyritized granodiorite from the dump of a hydrothermal Au–Te-bearing ore deposit. If you start seeing jarosite, chlorargyrite, rodalquilarite in float, you are in the right ground. Typical habit: cubic crystals, octahedral crystals. 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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