Garrelsite is a very rare borosilicate mineral typically found in evaporite deposits within lacustrine sedimentary basins. It most commonly occurs as small, colorless or white prismatic crystals or radial clusters, often associated with other borate minerals. Collectors primarily seek it from the famous Green River Formation in the United States.
Is this garrelsite?
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 garrelsite with a known reference. Garrelsite sits at Mohs 5-6 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Garrelsite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Garrelsite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: colorless, white, yellowish.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: prismatic crystals, radial aggregates.
Often confused with
Garrelsite vs. its common look-alikes — and how to tell them apart in the field.
Often found alongside garrelsite
Minerals reported to co-occur with garrelsite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Ba₃NaSi₂B₇O₁₆(OH)₄
- Mohs hardness
- 5-6
- Density
- 3.35 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Monoclinic
- Crystal habit
- Prismatic Crystals, Radial Aggregates
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Evaporitic Sedimentary Rocks
- Typical price
- $50-300 per specimen
Where rockhounds find garrelsite
Classic worldwide localities
- Green River Formation, USA
- Boron, California, USA
Field-hunting tip
Look in evaporitic sedimentary rocks country — that is the host setting where garrelsite typically forms. If you start seeing searlesite, reedmergnerite, borax in float, you are in the right ground. Field specimens usually show a prismatic crystals, radial aggregates habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find garrelsite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
