| Mineral | MARCASITE |
| Chemistry | FeS 2 |
| Color | Pale brass-Yellow tin-white on fresh exposures. |
| Luster | Metallic |
| CrystalSystem | Orthorhombic |
| CrystalHabits | include the tabular, bladed or prismatic forms. A twinning effect produces spear shaped crystal and repeated twinning produces a cock s comb cluster.Also massive, botryoidal, stalactitic and nodular. Sometimes as a replacement mineral of fossils and a pseudomorph of pyrite. |
| Cleavage | Distinct/Good Distinct on {101}. |
| Fracture | poor in two directions. |
| Hardness | 6 - 6½ |
| SpecificGravity | 4.91 g/ccm |
| Streak | Dark-grey to black. |
| AssociatedMinerals | Most frequently found in sedimentary rocks and coal bedsas a replacement mineral forming fossilsit is a mineral of low-temperaturenear-surfaceenvironmentsforming from acid solutions. Pyritethe more stable form of FeS^2forms under conditions of higher temperatures and lower acidity or alkaline environments. |
| Characteristics | A sulfur smell is sometimes detectable. |
| Occurences | widespread, but the more notable sites include Joplin, Missouri; Grant County, Wisconsin and Hardin County, Illinios, USA; Guanajuato, Mexico; Escale Pas de Calais, France; Peru; China and Russia. |
| Indicators | crystal habit, smell and greenish tint. |
| DensityNote | average for metallic minerals |
| IMAStatus | Approved |
| CellParameters | a = 4.436b = 5.414c = 3.381 |
| Ratio | a:b:c = 0.819 : 1 : 0.624 |
| Synonyms | Alasanit Alasanita Alasanite Alazanit Alazanita Alazanite Binarit Binarita Binarite Binarkies Hydropyrit Hydropyrita Hydropyrite Kammkies Lebererz (of Agricola) Marcasit Marcasita Markasit Maxy Poopyrites Prismatic Iron Pyrites Radiated Pyrites Spear |
| Strunz | 2/D.20-10 2 : Sulphides D : Sulphides with metal: sulphurselenium and tellurium 20 : Markasite - Iridarsenite series |
