Magnesite is a magnesium carbonate mineral that typically forms massive, porcelain-like white nodules rather than well-developed crystals. It is frequently associated with serpentine rocks and is often used as a substitute for more expensive white stones in lapidary work.
Is this magnesite?
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 magnesite with a known reference. Magnesite sits at Mohs 3.5-4.5, 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.
- 4Match the color rangeCompare against the expected color range: white, gray, yellow, brown, colorless, grayish white, yellowish white, brownish white.
- 5Look at form & habitCrystal system: trigonal. Typical habit: earthy, massive.
Often confused with
Magnesite vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside magnesite
Minerals reported to co-occur with magnesite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- MgCO₃
- Mohs hardness
- 3.5-4.5
- Density
- 3.00 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Transparent to translucent
- Crystal system
- Trigonal
- Crystal habit
- Earthy, massive
- Cleavage
- On {1011}, perfect
- Fluorescence
- Blue white under SW UV; bright blue white under LW UV
- Rarity
- Common
- Uses
- Industrial, Collector, Lapidary
- Host rock
- A primary mineral in igneous or sedimentary rocks; formed by metamorphism or alteration of serpentine and peridotite; uncommon in marine evaporites and hydrothermal veins; rare in carbonatites
Where rockhounds find magnesite
6 mapped spotsClassic worldwide localities
- A Gabbs, Gabbs district, Nye Co., Nevada, USA
- California, as in the Red Mountain district, Stanislaus and Santa Clara Co., USA
- Southwest of Chewelah, Stevens Co., Washington, USA
- Magnesia, Greece
- Baldissero Canavese, Piedmont, Italy
- Sunk, near Trieben, Styria, and Radenthein, Carinthia, Austria
Field-hunting tip
Where it forms: A primary mineral in igneous or sedimentary rocks; formed by metamorphism or alteration of serpentine and peridotite; uncommon in marine evaporites and hydrothermal veins; rare in carbonatites. If you start seeing talc, antigorite, chlorite in float, you are in the right ground. Typical habit: earthy, massive. Train your eye for that shape before scanning the outcrop. In the U.S., the densest reported localities are in Maryland, Pennsylvania, New Jersey. Start trip planning there.
More magnesite photos
Common questions
How do you identify magnesite?+
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Can I find magnesite in the United States?+
What rocks look like magnesite?+
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Find magnesite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
