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. Magnesite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Magnesite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: white, gray, yellow, brown, colorless.
- 5Look at form & habitCrystal system: trigonal. Typical habit: massive, granular, cryptocrystalline, rarely rhombohedral crystals.
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
- 3.0 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Translucent
- Crystal system
- Trigonal
- Crystal habit
- Massive, Granular, Cryptocrystalline, Rarely Rhombohedral Crystals
- Cleavage
- Perfect Rhombohedral
- Fluorescence
- Often White to Light Green Under SW UV
- Rarity
- Common
- Uses
- Industrial, Collector, Lapidary
- Host rock
- Ultramafic Rocks, Hydrothermal Veins, Sedimentary Evaporite Deposits
- Typical price
- $5-30 for specimens, $10-50 for lapidary material
Where rockhounds find magnesite
6 mapped spotsClassic worldwide localities
- Austria
- Brazil
- China
- Greece
- USA
- Australia
Field-hunting tip
Look in ultramafic rocks, hydrothermal veins, sedimentary evaporite deposits country — that is the host setting where magnesite typically forms. If you start seeing dolomite, calcite, serpentine in float, you are in the right ground. Field specimens usually show a massive, granular, cryptocrystalline, rarely rhombohedral crystals habit, so 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.
Common questions
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Find magnesite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
