Hanksite is a rare sulfate-carbonate evaporite mineral best known for its sharp, hexagonal crystal forms that are often found in alkaline lake deposits. It is famous among collectors for its intense and distinctive yellow-green fluorescence under ultraviolet light. These crystals are typically water-soluble and must be stored in dry, moisture-controlled environments to prevent degradation.
Is this hanksite?
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 hanksite with a known reference. Hanksite sits at Mohs 3-3.5, 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 to dull.
- 4Match the color rangeCompare against the expected color range: colorless, gray, grayish black, yellow, yellowish white.
- 5Look at form & habitCrystal system: hexagonal. Typical habit: crystalline.
Often confused with
Hanksite vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside hanksite
Minerals reported to co-occur with hanksite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Na₂₂K(SO₄)₉(CO₃)₂Cl
- Mohs hardness
- 3-3.5
- Density
- 2.562 g/cm³
- Streak
- White
- Luster
- Vitreous to dull
- Transparency
- Transparent to translucent
- Crystal system
- Hexagonal
- Crystal habit
- Crystalline
- Cleavage
- On {0001}, good
- Fluorescence
- Weak yellow under LW UV
- Rarity
- Rare
- Uses
- Collector
- Host rock
- In lacustrine evaporite deposits
Where rockhounds find hanksite
2 mapped spotsClassic worldwide localities
- Searles Lake, San Bernardino Co., California, USA
- Soda Lake, San Luis Obispo Co., California, USA
- Mono Lake, Mono Co., California, USA
- Death Valley, Inyo Co, California, USA
Field-hunting tip
Where it forms: In lacustrine evaporite deposits. If you start seeing halite, borax, trona in float, you are in the right ground. Typical habit: crystalline. Train your eye for that shape before scanning the outcrop. In the U.S., the densest reported localities are in California. Start trip planning there.
Common questions
How do you identify hanksite?+
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Can I find hanksite in the United States?+
What rocks look like hanksite?+
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Find hanksite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
