Tincalconite is a common dehydration product of borax, often forming as a white, powdery coating on borax crystals exposed to air. It is most frequently found as pseudomorphs replacing the original borax crystals while retaining their shape. Collectors typically find it in arid salt lake deposits alongside other borate minerals.
Is this tincalconite?
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 tincalconite with a known reference. Tincalconite sits at Mohs 2, 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: white.
- 5Look at form & habitCrystal system: trigonal. Typical habit: cryptocrystalline.
Often confused with
Tincalconite vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside tincalconite
Minerals reported to co-occur with tincalconite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Na₂B₄O₇·5H₂O
- Mohs hardness
- 2
- Density
- 1.880 g/cm³
- Colors
- Streak
- White
- Luster
- Vitreous to dull
- Transparency
- Transparent to translucent
- Crystal system
- Trigonal
- Crystal habit
- Cryptocrystalline
- Cleavage
- None
- Fluorescence
- White under SW and LW UV
- Rarity
- Common
- Uses
- Collector, Scientific research
- Host rock
- Typically a dehydration product of other borates
Where rockhounds find tincalconite
Classic worldwide localities
- Kramer borate deposit, Boron, Kern Co. and as crystals at Searles Lake, San Bernardino Co., California, USA
- Tincalayu borax deposit, Salar del Hombre Muerto, Salta Province, Argentina
- Kirka borate deposit, Eskiçehir Province, Turkey
- Larderello, Val di Cecina, Tuscany, Italy
- Mud volcanoes, Kerch Peninsula, Ukraine
Field-hunting tip
Where it forms: Typically a dehydration product of other borates. If you start seeing borax, kernite in float, you are in the right ground. Typical habit: cryptocrystalline. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify tincalconite?+
Where is tincalconite found?+
What rocks look like tincalconite?+
What minerals are found with tincalconite?+
What kind of rock does tincalconite form in?+
What is tincalconite used for?+
Find tincalconite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
