Ginorite is a rare calcium borate mineral typically found as white, pearly platy crystals or foliated masses. It is most commonly associated with geothermal borate occurrences, particularly in the Tuscany region of Italy, where it forms in evaporite environments.
Is this ginorite?
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 ginorite with a known reference. Ginorite 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: white.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous.
- 4Match the color rangeCompare against the expected color range: white.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: platy crystals, foliated aggregates, or scales.
Often confused with
Ginorite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Ginorite is noticeably harder (Mohs 3.5 vs. 1.5-2); luster reads vitreous on Ginorite and subvitreous, pearly on {010} cleavages, silky if fibrous on Gypsum.
How to tell apart: Colemanite is the harder of the two (Mohs 4.5 vs. 3.5).
How to tell apart: Ginorite is noticeably harder (Mohs 3.5 vs. 2.5).
Often found alongside ginorite
Minerals reported to co-occur with ginorite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Ca₂B₁₄O₂₃·8H₂O
- Mohs hardness
- 3.5
- Density
- 2.07-2.14 g/cm³
- Colors
- Streak
- White
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Monoclinic
- Crystal habit
- Platy crystals, foliated aggregates, or scales
- Cleavage
- On {010}, perfect
- Rarity
- Rare
- Uses
- Collector
- Host rock
- As efflorescences on weathered basalt associated with colemanite-bearing limestone (Death Valley, California, USA); in veins in sandstone (Sasso Pisano, Italy)
Where rockhounds find ginorite
Classic worldwide localities
- Mott colemanite prospect and on the Hard Scramble claim, Furnace Creek district, Death Valley, Inyo Co., California, USA
- Sasso Pisano, eight km south of Lardarello, Tuscany, Italy
- Clinton quarry, Windsor, Nova Scotia, Canada
- Tincalayu borax deposit, Salar del Hombre Muerto, Salta Province, Argentina
- Chalkar salt dome, Ak-saı̆ Valley, Uralsk district, Kazakhstan
Field-hunting tip
Where it forms: As efflorescences on weathered basalt associated with colemanite-bearing limestone (Death Valley, California, USA); in veins in sandstone (Sasso Pisano, Italy). If you start seeing calcite, mirabilite, gypsum in float, you are in the right ground. Typical habit: platy crystals, foliated aggregates, or scales. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify ginorite?+
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What rocks look like ginorite?+
What minerals are found with ginorite?+
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Find ginorite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
