Frankhawthorneite is a rare copper tellurate mineral typically found as small, dark green to black tabular crystals. It is primarily known from the Centennial Eureka mine in Utah, where it occurs as a secondary mineral in oxidized tellurium-rich ore zones.
Is this frankhawthorneite?
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 frankhawthorneite with a known reference. Frankhawthorneite 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. Frankhawthorneite leaves a pale green streak.
- 3Read the lusterHold the specimen under a strong light. Frankhawthorneite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: dark green, black.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: tabular crystals.
Often confused with
Frankhawthorneite vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Streak differs — Frankhawthorneite leaves pale green, Quetzalcoatlite leaves yellow.
How to tell apart: Frankhawthorneite is noticeably harder (Mohs 3-4 vs. 1-2); streak differs — Frankhawthorneite leaves pale green, Tlapallite leaves yellow; luster reads vitreous on Frankhawthorneite and resinous on Tlapallite.
Often found alongside frankhawthorneite
Minerals reported to co-occur with frankhawthorneite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Cu₂TeO₄(OH)₂
- Mohs hardness
- 3-4
- Density
- 4.99 g/cm³
- Colors
- Streak
- Pale Green
- Luster
- Vitreous
- Transparency
- Translucent
- Crystal system
- Monoclinic
- Crystal habit
- Tabular Crystals
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Tellurium-bearing Hydrothermal Deposits
- Typical price
- $100-500 for small thumbnail specimens
Where rockhounds find frankhawthorneite
Classic worldwide localities
- Centennial Eureka mine, Utah, USA
Field-hunting tip
Look in tellurium-bearing hydrothermal deposits country — that is the host setting where frankhawthorneite typically forms. If you start seeing emmonsite, rodalquilarite, teineite in float, you are in the right ground. Field specimens usually show a tabular crystals habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find frankhawthorneite on the map
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