Skarn is a metasomatic rock formed through the interaction of hot hydrothermal fluids with carbonate-rich rocks like limestone or dolostone. Collectors prize skarns for their diverse and often showy mineral assemblages, which frequently include large crystals of garnet, pyroxene, and epidote.
Hardness
5-7
Mohs
Luster
Vitreous
Transparency
Translucent
Is this skarn?
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 skarn with a known reference. Skarn sits at Mohs 5-7, softer than the next harder reference, harder than the previous one.
- 2Read the textureLook at a fresh break with a hand lens. Grain size: Coarse-grained.
- 3Pick out the mineralsComposition: Calc-silicate minerals dominated by garnet and pyroxene, with idocrase, wollastonite, actinolite, magnetite, epidote and scapolite. Identify the two or three most abundant grains.
- 4Read the lusterHold the specimen under a strong light. Luster: vitreous.
- 5Match the color rangeCompare against the expected color range: green, brown, black, white, red.
Often found alongside skarn
Minerals reported to co-occur with skarn. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Mohs hardness
- 5-7
- Density
- 2.8-3.6 g/cm³
- Luster
- Vitreous
- Transparency
- Translucent
- Rarity
- Common
- Uses
- Collector, Industrial
- Host rock
- metasomatized carbonate rocks
- Grain size
- Coarse-grained
- Composition
- Calc-silicate minerals dominated by garnet and pyroxene, with idocrase, wollastonite, actinolite, magnetite, epidote and scapolite
Where rockhounds find skarn
Classic worldwide localities
- Sweden
- USA
- Mexico
- Russia
- China
Field-hunting tip
Where it forms: metasomatized carbonate rocks. If you start seeing garnet, pyroxene, epidote in float, you are in the right ground.
Common questions
How do you identify skarn?+
Mohs hardness is 5-7. Composition: Calc-silicate minerals dominated by garnet and pyroxene, with idocrase, wollastonite, actinolite, magnetite, epidote and scapolite. Luster: vitreous. Common colors include green, brown, black, white.
Where is skarn found?+
Notable localities include Sweden; USA; Mexico; Russia; China.
What minerals are found with skarn?+
Skarn commonly co-occurs with garnet, pyroxene, epidote, vesuvianite, wollastonite. Spotting any of these in float or country rock is a useful trip signal.
What kind of rock does skarn form in?+
Where it forms: metasomatized carbonate rocks. Working float back to the host body is the standard way to chase a fresh occurrence.
What is skarn used for?+
Skarn is used in collector, industrial.
Find skarn on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
