Antigorite is a common member of the serpentine group, often appearing as massive or platy, foliated green aggregates. It is a primary constituent of serpentinite rocks and is typically found in altered ultramafic environments where magnesium-rich rocks have undergone metamorphism.
Is this antigorite?
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 antigorite with a known reference. Antigorite sits at Mohs 2.5-3.5 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Antigorite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Antigorite typically shows a greasy luster.
- 4Match the color rangeCompare against the expected color range: green, yellow-green, brown, white.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: platy to fibrous, often massive or foliated.
Often confused with
Antigorite vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Luster reads greasy on Antigorite and silky on Chrysotile.
How to tell apart: Antigorite is noticeably harder (Mohs 2.5-3.5 vs. 1); luster reads greasy on Antigorite and pearly on Talc.
Often found alongside antigorite
Minerals reported to co-occur with antigorite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Mg₃Si₂O₅(OH)₄
- Mohs hardness
- 2.5-3.5
- Density
- 2.5-2.6 g/cm³
- Streak
- White
- Luster
- Greasy
- Transparency
- Translucent
- Crystal system
- Monoclinic
- Crystal habit
- Platy to Fibrous, Often Massive or Foliated
- Cleavage
- Perfect Basal
- Rarity
- Common
- Uses
- Collector, Lapidary
- Host rock
- Metamorphic Serpentinites
- Typical price
- $5-50 for hand specimens
Where rockhounds find antigorite
Classic worldwide localities
- Antigorio Valley, Italy
- Valmalenco, Italy
- Thetford Mines, Canada
- Snarum, Norway
- California, USA
Field-hunting tip
Look in metamorphic serpentinites country — that is the host setting where antigorite typically forms. If you start seeing chromite, magnetite, diopside in float, you are in the right ground. Field specimens usually show a platy to fibrous, often massive or foliated habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find antigorite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
