Stringhamite is a rare calcium copper silicate typically found as small, bright blue to blue-green tabular crystals. It is most famous for its occurrences in Utah, where it forms in cavities within skarn deposits and hydrothermal veins. Collectors prize it for its vibrant color and distinct crystal morphology.
Is this stringhamite?
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 stringhamite with a known reference. Stringhamite sits at Mohs 3, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: light blue.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous.
- 4Match the color rangeCompare against the expected color range: azure, blue violet, dark blue.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: aggregates.
Often confused with
Stringhamite vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside stringhamite
Minerals reported to co-occur with stringhamite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- CaCuSiO₄·H₂O
- Mohs hardness
- 3
- Density
- 3.16-3.18 g/cm³
- Streak
- Light blue
- Luster
- Vitreous
- Transparency
- Transparent to translucent
- Crystal system
- Monoclinic
- Crystal habit
- Aggregates
- Cleavage
- Good on {001}; imperfect on {100}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- A retrograde reaction product between copper-bearing solutions and diopside in diopside-magnetite tactites (Bawana mine, Utah, USA)
Where rockhounds find stringhamite
Classic worldwide localities
- Bawana mine, about six km northwest of Milford, Beaver Co., Utah, USA
- Crestmore, Riverside Co., California, USA
- Christmas copper mine, Gila Co., Arizona, USA
- El Bronce mine, Tierra Amarilla, Copiapó, Chile
Field-hunting tip
Where it forms: A retrograde reaction product between copper-bearing solutions and diopside in diopside-magnetite tactites (Bawana mine, Utah, USA). If you start seeing thaumasite, tenorite, kinoite in float, you are in the right ground. Typical habit: aggregates. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify stringhamite?+
Where is stringhamite found?+
Is stringhamite safe to handle?+
What rocks look like stringhamite?+
What minerals are found with stringhamite?+
What kind of rock does stringhamite form in?+
What is stringhamite used for?+
Find stringhamite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
