Marcasite
The name Marcasite is derived from Arabic word for
pyrite. Marcasite and
pyrite are polymorphs. Marcasite is lighter and more brittle than
pyrite.
Marcasite forms metallic pale brass-yellow coloured, tabular or pyramidal, sometimes stalactic or globular crystals. On fresh surfaces it is pale yellow to almost white and has a bright metallic lustre.
| General Information |
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| Chemical Formula | Michael O’Donoghue, Gems, Sixth Edition (2006) More from other references |
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| Photos of natural/un-cut material from mindat.org |
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| Physical Properties of Marcasite |
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| Mohs Hardness | 6 to 6.5Ulrich Henn and Claudio C. Milisenda, Gemmological Tables (2004) More from other references |
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| Specific Gravity | 4.80 to 4.90Ulrich Henn and Claudio C. Milisenda, Gemmological Tables (2004) More from other references |
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| Tenacity | BrittleArthur Thomas, Gemstones (2009) |
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| Cleavage Quality | PoorArthur Thomas, Gemstones (2009) |
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| Fracture | UnevenArthur Thomas, Gemstones (2009) |
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| Optical Properties of Marcasite |
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| Refractive Index | NilArthur Thomas, Gemstones (2009) |
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| Birefringence | NilArthur Thomas, Gemstones (2009) |
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| Pleochroism | NilArthur Thomas, Gemstones (2009) More from other references |
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| Dispersion | NilArthur Thomas, Gemstones (2009) |
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| Colour |
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| Colour (General) | Yellow, bronze colourUlrich Henn and Claudio C. Milisenda, Gemmological Tables (2004) More from other references |
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| Transparency | OpaqueUlrich Henn and Claudio C. Milisenda, Gemmological Tables (2004) More from other references |
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| Lustre | MetallicMichael O’Donoghue, Gems, Sixth Edition (2006) More from other references |
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| Crystallography of Marcasite |
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| Crystal System | OrthorhombicUlrich Henn and Claudio C. Milisenda, Gemmological Tables (2004) More from other references |
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| Habit | Typically tabular but may be pyramidal
or prismatic and may show curved facesMichael O’Donoghue, Gems, Sixth Edition (2006) More from other references |
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| Geological Environment |
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| Where found: | Marcasite occurs in sedimentary environments formed characteristically under low temperature, highly acidic conditions.Michael O’Donoghue, Gems, Sixth Edition (2006) |
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| Further Information |
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| Mineral information: | Marcasite information at mindat.org |
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| Significant Gem Localities |
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| Myanmar | | |
| Ted Themelis (2008) Gems & mines of Mogok |
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