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, 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.
