Esquireite is a rare barium silicate mineral primarily known from the Big Creek mining district in California. It typically occurs as colorless to white thin, platy crystals associated with sanbornite in metamorphic assemblages.
Is this esquireite?
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 esquireite with a known reference. Esquireite 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 to pearly.
- 4Match the color rangeCompare against the expected color range: colorless.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: platy crystals.
Often confused with
Esquireite vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside esquireite
Minerals reported to co-occur with esquireite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- BaSi₆O₁₃·7H₂O
- Mohs hardness
- ~2
- Density
- 2.18 g/cm³
- Colors
- Streak
- White
- Luster
- Vitreous to pearly
- Transparency
- Transparent
- Crystal system
- Monoclinic
- Crystal habit
- Platy crystals
- Cleavage
- Perfect on {001}, fair on {100}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Formed by low-temperature hydrothermal alteration of sanbornite, during contact metamorphism of Ba-rich sediments
Where rockhounds find esquireite
Classic worldwide localities
- Esquire #1 claim, near Rush Creek and the Esquire #8 claim, on Big Creek, eastern Fresno County and on the NW slope of Trumbull Peak, Mariposa County, California, USA
Field-hunting tip
Where it forms: Formed by low-temperature hydrothermal alteration of sanbornite, during contact metamorphism of Ba-rich sediments. If you start seeing cerchiaraite-, kampfite, macdonaldite in float, you are in the right ground. Typical habit: platy crystals. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify esquireite?+
Where is esquireite found?+
What rocks look like esquireite?+
What minerals are found with esquireite?+
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Find esquireite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
