Giorgiosite is a rare magnesium carbonate mineral that typically forms as soft, chalky white crusts or powdery aggregates. It is primarily found in volcanic fumarolic environments and is structurally related to the hydromagnesite group. Collectors should look for fine-grained white coatings on volcanic rock surfaces.
Is this giorgiosite?
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 giorgiosite with a known reference. Giorgiosite 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. Giorgiosite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Giorgiosite typically shows a dull luster.
- 4Match the color rangeCompare against the expected color range: white.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: crusts, earthy aggregates.
Often confused with
Giorgiosite vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Hydromagnesite is the harder of the two (Mohs 3.5 vs. 2); luster reads dull on Giorgiosite and pearly on Hydromagnesite.
How to tell apart: Magnesite is the harder of the two (Mohs 3.5-4.5 vs. 2); luster reads dull on Giorgiosite and vitreous on Magnesite.
Often found alongside giorgiosite
Minerals reported to co-occur with giorgiosite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Mg₅(CO₃)₄(OH)₂·5H₂O
- Mohs hardness
- 2
- Density
- 2.12 g/cm³
- Colors
- Streak
- White
- Luster
- Dull
- Transparency
- Opaque
- Crystal system
- Monoclinic
- Crystal habit
- Crusts, Earthy Aggregates
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Fumarole Deposits
- Typical price
- $20-100 per specimen
Where rockhounds find giorgiosite
Classic worldwide localities
- Greece
- Italy
- Austria
Field-hunting tip
Look in fumarole deposits country — that is the host setting where giorgiosite typically forms. If you start seeing hydromagnesite, aragonite, calcite in float, you are in the right ground. Field specimens usually show a crusts, earthy aggregates habit, so train your eye for that shape before scanning the outcrop.
Common questions
How do you identify giorgiosite?+
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How much is giorgiosite worth?+
What rocks look like giorgiosite?+
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Find giorgiosite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
