Searlesite is a rare borosilicate mineral typically found in evaporite deposits within ancient lake beds. Collectors should look for its characteristic bladed or radiating crystal clusters occurring within saline crusts.
Is this searlesite?
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 searlesite with a known reference. Searlesite 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. Searlesite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Searlesite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: white, colorless, gray.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: bladed crystals, radial aggregates, fibrous.
Often confused with
Searlesite vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Luster reads vitreous on Searlesite and dull on Priceite.
How to tell apart: Luster reads vitreous on Searlesite and subvitreous on Howlite.
How to tell apart: Searlesite is noticeably harder (Mohs 3.5 vs. 2.5); luster reads vitreous on Searlesite and silky on Ulexite.
Often found alongside searlesite
Minerals reported to co-occur with searlesite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- NaBSi₂O₅(OH)₂
- Mohs hardness
- 3.5
- Density
- 2.44 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Monoclinic
- Crystal habit
- Bladed Crystals, Radial Aggregates, Fibrous
- Cleavage
- Perfect On {110}
- Rarity
- Uncommon
- Uses
- Collector
- Host rock
- Evaporite Deposits in Lacustrine Basins
- Typical price
- $15-60 for small mineral specimens
Where rockhounds find searlesite
1 mapped spotsClassic worldwide localities
- Searles Lake, California, USA
- Boron, California, USA
- Green River Formation, Wyoming, USA
- Tuscany, Italy
Field-hunting tip
Look in evaporite deposits in lacustrine basins country — that is the host setting where searlesite typically forms. If you start seeing borax, trona, halite in float, you are in the right ground. Field specimens usually show a bladed crystals, radial aggregates, fibrous habit, so train your eye for that shape before scanning the outcrop. In the U.S., the densest reported localities are in New Mexico — start trip planning there.
Common questions
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Find searlesite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
