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.

Hardness

3.5

Mohs

Luster

Vitreous

Streak

White

Transparency

Transparent

mineralrarenull family

Esquireite

Hardness: 3.5
Luster: Vitreous
Streak: White
Transparency: Transparent

Is this esquireite?

5-step field check

Run through these checks against the specimen in your hand. The more boxes tick, the more confident the ID.

1
Test the hardness
Try to scratch esquireite with a known reference. Esquireite sits at Mohs 3.5 — softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Esquireite leaves a white streak.
3
Read the luster
Hold the specimen under a strong light. Esquireite typically shows a vitreous luster.
4
Match the color range
Compare against the expected color range: colorless, white.
5
Look at form & habit
Crystal system: monoclinic. Typical habit: platy crystals.

Often confused with

Esquireite vs. its common look-alikes — and how to tell them apart in the field.

mineral

Sanbornite

Mohs 5

How to tell apart: Sanbornite is the harder of the two (Mohs 5 vs. 3.5).

How to tell apart: Celsian is the harder of the two (Mohs 6 vs. 3.5).

Compare →

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: BaSi₆O₁₃·3H₂O
Mohs hardness: 3.5
Density: 2.84 g/cm³
Colors: Colorless White
Streak: White
Luster: Vitreous
Transparency: Transparent
Crystal system: Monoclinic
Crystal habit: Platy Crystals
Cleavage: Perfect On {001}
Rarity: Rare
Uses: Collector
Host rock: Metamorphosed Sanbornite-bearing Rocks
Typical price: $50-300 per specimen

Where rockhounds find esquireite

Classic worldwide localities

Baumgartner quarry, Fresno County, California, USA

Field-hunting tip

Look in metamorphosed sanbornite-bearing rocks country — that is the host setting where esquireite typically forms. If you start seeing sanbornite, quartz, fresnoite in float, you are in the right ground. Field specimens usually show a platy crystals habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify esquireite?+

Mohs hardness is 3.5. It typically shows a vitreous luster. The streak is white. Common colors include colorless, white.

Where is esquireite found?+

Notable localities include Baumgartner quarry, Fresno County, California, USA.

How much is esquireite worth?+

Typical asking prices fall in the range of $50-300 per specimen. Quality, size, and provenance can move individual specimens well outside that range.

What rocks look like esquireite?+

Esquireite is most often confused with Sanbornite, Celsian. A quick hardness test and a streak check separate the look-alikes faster than color alone.

What minerals are found with esquireite?+

Esquireite commonly co-occurs with sanbornite, quartz, fresnoite, traskite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does esquireite form in?+

Esquireite typically forms in metamorphosed sanbornite-bearing rocks. Working float back to the host body is the standard way to chase a fresh occurrence.

What is esquireite used for?+

Esquireite is used in collector.

Find esquireite on the map

RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.