Definition of marcasite in English:

marcasite

noun

  • 1A semiprecious stone consisting of pyrite.

    • ‘Stones and metals fall under the rulership of planets, not signs, but through its association with Venus, Libra has affinity with copper, sapphires, marcasite, lapis lazuli and chrysolite.’
    • ‘Laurie's hand automatically moves to cover the silver brooch, fingers tracing the elaborate curling leaves encrusted with marcasite.’
    • ‘Access to the pit is prohibited, but excellent specimens of calcite scalenohedra, dolomite rhombohedra, pyrite, and marcasite have been collected from the pit's east wall.’
    • ‘Other minerals mentioned from the mine by Dunham include galena, sphalerite, pyrite, chalcedony, and minor marcasite and pyrrhotite.’
    • ‘Two small dumps are exposed, affording an opportunity to collect some of the attractive microcrystals of rhodochrosite and crystals of apatite, gypsum, barite, goethite, marcasite, calcite, and chalcocite that are found there.’
    1. 1.1 A bronze-yellow mineral consisting of iron disulfide but differing from pyrite in typically forming aggregates of tabular crystals.
      • ‘The fine-grained sediment of the matrix consists chiefly of pyrite or marcasite, and their surfaces are often covered with outward-projecting crystals of pyrite or marcasite.’
      • ‘The bodies of iron sulfide nodules in the Olentangy Shale are composed of fine-grained pyrite, and their surfaces are frequently covered with tabular crystals of marcasite.’
      • ‘Sphalerite stalactites to 15 cm in diameter and coated with crystallized marcasite and galena are reported from the Marsden prospect near Galena, Illinois.’
      • ‘We have also noted clumps of small marcasite crystals as a late-stage association with galena and drusy quartz from the Eagle mine.’
      • ‘Although the matrix is known to contain mainly pyrite, other sulfides are also present, such as marcasite and a presently unidentified silver-gray mineral coating the interiors of the flow tubes.’
    2. 1.2 A piece of polished steel or a similar metal cut as a gem.

Origin

Late Middle English: from medieval Latin marcasita, from Arabic marḳašīṯa, from Persian.

Pronunciation

marcasite

/ˈmärkəˌsīt/