Lapis is a deep blue semi-precious stone prized since antiquity for its intense color. The intense blue color is due to the presence of the trisulfur (S3) radical anion in the crystal. Lapis lazuli is a rock whose most important mineral component is lazurite. Most lapis lazuli also contains calcite (white), sodalite (blue), and pyrite (metallic yellow). Lapis takes an excellent polish and can be made into jewelry, carvings, boxes, mosaics, ornaments, small statues, and vases.
Marcasite The mineral marcasite, sometimes called white iron pyrite, is iron sulfide (FeS2) with orthorhombic crystal structure. On fresh surfaces it is pale yellow to almost white and has a bright metallic luster. It tarnishes to a yellowish or brownish color and gives a black streak. It is a brittle material that cannot be scratched with a knife. It typically forms under low-temperature highly acidic conditions.