— marcasitical /mahr'keuh sit"i keuhl/ , adj.
/mahr"keuh suyt'/ , n.
1. a common mineral, iron disulfide, FeS 2 , chemically similar to pyrite but crystallizing in the orthorhombic system.
2. any of the crystallized forms of iron pyrites, much used in the 18th century for ornaments.
3. a specimen or ornament of this substance.
[ 1375-1425; late ME marcasita marqashita marqashita ]