Monohydrocalcite is an uncommon hydrated calcium carbonate mineral that typically forms in evaporitic environments, alkaline lakes, or occasionally as a cave deposit. It is metastable and often converts to calcite over time if dehydrated, so collectors should store specimens in sealed containers to preserve their integrity.
Is this monohydrocalcite?
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 monohydrocalcite with a known reference. Monohydrocalcite sits at Mohs 3 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Monohydrocalcite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Monohydrocalcite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: white, colorless, gray, yellowish.
- 5Look at form & habitCrystal system: trigonal. Typical habit: hexagonal prisms, spherulitic aggregates, crusts.
Often confused with
Monohydrocalcite vs. its common look-alikes — and how to tell them apart in the field.
Often found alongside monohydrocalcite
Minerals reported to co-occur with monohydrocalcite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- CaCO₃·H₂O
- Mohs hardness
- 3
- Density
- 2.44 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Translucent
- Crystal system
- Trigonal
- Crystal habit
- Hexagonal Prisms, Spherulitic Aggregates, Crusts
- Cleavage
- Perfect
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Saline Lake Sediments and Cave Environments
- Typical price
- $20-100 per specimen
Where rockhounds find monohydrocalcite
Classic worldwide localities
- Lake Issyk-Kul, Kyrgyzstan
- Green River Formation, USA
- Cave deposits, Australia
Field-hunting tip
Look in saline lake sediments and cave environments country — that is the host setting where monohydrocalcite typically forms. If you start seeing calcite, aragonite, halite in float, you are in the right ground. Field specimens usually show a hexagonal prisms, spherulitic aggregates, crusts habit, so train your eye for that shape before scanning the outcrop.
Common questions
How do you identify monohydrocalcite?+
Where is monohydrocalcite found?+
How much is monohydrocalcite worth?+
What rocks look like monohydrocalcite?+
What minerals are found with monohydrocalcite?+
What kind of rock does monohydrocalcite form in?+
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Find monohydrocalcite on the map
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