Inyoite is a rare hydrated calcium borate mineral that forms as prismatic crystals or radiating clusters within evaporite deposits. Collectors typically look for its sharp, glassy crystals in classic borate-rich environments where it is often associated with other borate species.
Is this inyoite?
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 inyoite with a known reference. Inyoite sits at Mohs 2, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: white.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous.
- 4Match the color rangeCompare against the expected color range: white, pinkish white.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: massive, spherical, tabular.
Often confused with
Inyoite vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside inyoite
Minerals reported to co-occur with inyoite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Ca₂B₆O₆(OH)₁₀·8H₂O
- Mohs hardness
- 2
- Density
- 1.875 g/cm³
- Colors
- Streak
- White
- Luster
- Vitreous
- Transparency
- Transparent, translucent on dehydration
- Crystal system
- Monoclinic
- Crystal habit
- Massive, spherical, tabular
- Cleavage
- {001}, good; {010}, distinct
- Rarity
- Uncommon
- Uses
- Collector
- Host rock
- Along fractures and nodular in sedimentary borate deposits; may be authigenic in playa sediments
Where rockhounds find inyoite
Classic worldwide localities
- An adit on Mount Blanco, Furnace Creek district, Death Valley, Inyo Co., and in the Kramer borate deposit, Boron, Kern Co., California, USA
- Hillsborough and Wentworth, New Brunswick, Canada
- Der boron deposit, Kazakhstan
- Bigadiç borate district, Balıkesir Province, Turkey
- Loma Blanca deposit, eight km southwest of Coranzulí, Jujuy Province, Argentina
- Tincalayu borax deposit, Salar del Hombre Muerto, and at the Monte Azul mine, south of Sijes, Salta Province, Argentina
Field-hunting tip
Where it forms: Along fractures and nodular in sedimentary borate deposits; may be authigenic in playa sediments. If you start seeing meyerhofferite, colemanite, priceite in float, you are in the right ground. Typical habit: massive, spherical, tabular. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify inyoite?+
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What rocks look like inyoite?+
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Find inyoite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
