Image: <bdi><a href="https://www.wikidata.org/wiki/Q56247090" class="extiw" title="d:Q56247090"><span title="mineral collector and dealer">Robert M. Lavinsky</span></a></bdi> (CC BY-SA 3.0)
orthorhombiccommonSulfides
Marcasite
FeS₂
The image displays a botryoidal to radiating aggregate of pale bronze-yellow marcasite, possibly intergrown with darker, reddish-brown hematite, forming an interesting textural specimen.
Marcasite Physical Properties
Mohs Hardness
6Crystal System
orthorhombicLuster
metallicStreak Color
dark grayish-blackCleavage
poor on {101}Fracture
uneven to conchoidalSpecific Gravity
4.8Colors
pale bronze-yellow, tin-white, yellowish, brownishTransparency
opaqueType Locality
Farafra Oasis, Matruh Governorate, EgyptMineral Group
SulfidesUses
collector's specimens, source of sulfur, minor ore of ironAssociated Minerals
pyrite, galena, sphalerite, calcite, dolomite, quartz, hematiteRarity
commonGeological Context
Marcasite typically forms in low-temperature, acidic environments, often found in sedimentary rocks such as shales, limestones, and coal beds, or as concretions. It is a metastable polymorph of pyrite and can readily decompose in humid air.
