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, 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.
