Jonesite is an extremely rare barium titanium silicate found almost exclusively in the San Benito River headwaters region of California. It typically appears as small, colorless to pale yellow tabular crystals perched on natrolite, often associated with the iconic blue benitoite and black neptunite.
Is this jonesite?
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 jonesite with a known reference. Jonesite sits at Mohs 3-4 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Jonesite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Jonesite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: colorless, white, pale yellow.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: tabular crystals, radiating aggregates.
Often confused with
Jonesite vs. its common look-alikes — and how to tell them apart in the field.
Often found alongside jonesite
Minerals reported to co-occur with jonesite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Ba₄Ti₂Si₆O₁₈(OH)₂·nH₂O
- Mohs hardness
- 3-4
- Density
- 3.2 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Monoclinic
- Crystal habit
- Tabular Crystals, Radiating Aggregates
- Cleavage
- Distinct On {001}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Glaucophane Schist Inclusions in Serpentinite
- Typical price
- $50-500 depending on crystal size and clarity
Where rockhounds find jonesite
Classic worldwide localities
- San Benito County, California, USA
Field-hunting tip
Look in glaucophane schist inclusions in serpentinite country — that is the host setting where jonesite typically forms. If you start seeing benitoite, neptunite, joaquinite in float, you are in the right ground. Field specimens usually show a tabular crystals, radiating aggregates habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find jonesite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
