Tangeite is a rare calcium-copper vanadate that typically forms as colorful, fibrous crusts or radial aggregates in vanadium-rich sedimentary environments. Collectors look for its distinctive pearly luster and vibrant olive-green to yellow hues, which distinguish it from more common members of the descloizite group.
Is this tangeite?
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 tangeite with a known reference. Tangeite sits at Mohs 3.5, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: light yellow green.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous, pearly on the cleavage.
- 4Match the color rangeCompare against the expected color range: yellow, yellow green, olive green.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: granular.
Often confused with
Tangeite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Tangeite leaves light yellow green, Descloizite leaves orange to brownish red; luster reads vitreous, pearly on the cleavage on Tangeite and greasy on Descloizite.
How to tell apart: Streak differs, so Tangeite leaves light yellow green, Mottramite leaves yellowish green; luster reads vitreous, pearly on the cleavage on Tangeite and greasy on Mottramite.
Often found alongside tangeite
Minerals reported to co-occur with tangeite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- CaCuVO₄(OH)
- Mohs hardness
- 3.5
- Density
- 3.75 g/cm³
- Streak
- Light yellow green
- Luster
- Vitreous, pearly on the cleavage
- Transparency
- Transparent
- Crystal system
- Orthorhombic
- Crystal habit
- Granular
- Cleavage
- {010}, perfect; {001}, good
- Rarity
- Rare
- Uses
- Collector
- Host rock
- A rare secondary mineral in vanadium-bearing mineral deposits in sandstone
Where rockhounds find tangeite
Classic worldwide localities
- Uranium, Roc Creek, Paradox Valley, at the Pluto mine, Bull Canyon, Uravan district, Montrose Co., and in the Shirley May mine, Garo district, Park Co., Colorado, USA
- Richardson district, Moab Valley, Grand Co., and in the Whirlwind mine, Monument Valley, San Juan Co., Utah, USA
- Monument Valley, on Garnet Ridge, Apache Co., and at the Monument No. 1 mine, Navajo Co., and in the Copper Queen mine, New Water Mountains, Yuma Co., Arizona, USA
- Mammoth copper mine, Grindstone Creek, Glenn Co., California, USA
- Tyuya-Muyun Cave, Fergana Valley, Alai Range, Kyrgyzstan
- Molinello manganese mine, near Chiavari, Val Graveglia, Liguria, Italy
Field-hunting tip
Where it forms: A rare secondary mineral in vanadium-bearing mineral deposits in sandstone. If you start seeing calcite, barite, malachite in float, you are in the right ground. Typical habit: granular. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify tangeite?+
Where is tangeite found?+
Is tangeite safe to handle?+
What rocks look like tangeite?+
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Find tangeite on the map
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