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. Hanksite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Hanksite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: colorless, white, yellow, gray.
- 5Look at form & habitCrystal system: hexagonal. Typical habit: tabular, hexagonal prisms with pyramidal terminations.
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
- 2.56 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Hexagonal
- Crystal habit
- Tabular, Hexagonal Prisms with Pyramidal Terminations
- Cleavage
- Distinct On {1011}
- Fluorescence
- Bright Yellow-green Under LW and SW UV
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Evaporite Lake Deposits
- Typical price
- $20-200 per specimen depending on crystal size and clarity
Where rockhounds find hanksite
1 mapped spotsClassic worldwide localities
- Searles Lake, California, USA
- Boron, California, USA
- Kalsitoye, Russia
Field-hunting tip
Look in evaporite lake deposits country — that is the host setting where hanksite typically forms. If you start seeing halite, borax, thenardite in float, you are in the right ground. Field specimens usually show a tabular, hexagonal prisms with pyramidal terminations habit, so 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
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Find hanksite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
