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 ~6, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: white.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous.
- 4Match the color rangeCompare against the expected color range: colorless.
- 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
- ~6
- Density
- 3.68 g/cm³
- Colors
- Streak
- White
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Monoclinic
- Crystal habit
- Prismatic crystals, radial aggregates
- Cleavage
- Perfect on {001}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Of authigenic origin, in dolomitic shale in drill core from the Green River Formation (Uintah Co., Utah, USA)
Where rockhounds find garrelsite
Classic worldwide localities
- Kramer borate deposit, Kern Co., and at Searles Lake, San Bernardino Co., California, USA
Field-hunting tip
Where it forms: Of authigenic origin, in dolomitic shale in drill core from the Green River Formation (Uintah Co., Utah, USA). If you start seeing nahcolite, shortite, searlesite in float, you are in the right ground. Typical habit: prismatic crystals, radial aggregates. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify garrelsite?+
Where is garrelsite found?+
What rocks look like garrelsite?+
What minerals are found with garrelsite?+
What kind of rock does garrelsite form in?+
What is garrelsite used for?+
Find garrelsite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
