page_title: Oligoclase
hierarchical_section_title: Oligoclase
caption_attribution_description: English: Oligoclase Locality: Pili Mine, Sonora, Mexico (Locality at mindat.org) Size: miniature, 4.5 x 3.4 x 3 cm Oligoclase (Moonstone) Very nice cluster of tabular Oligoclase crystals from the famous find of early in the 1990s. The best-formed and most prominent of the crystals displays the beautiful opalescent play of light that these crystals are so famous for. 4.5 x 3.4 x 3 cm Deutsch: Oligoklas Fundort: Pili Mine, Sonora , Mexiko (Fundort bei mindat.org) Größe: 4.5 x 3.4 x 3 cm
context_page_description: Oligoclase is a rock-forming mineral belonging to the plagioclase feldspars. In chemical composition and in its crystallographic and physical characters it is intermediate between albite and anorthite. The albite:anorthite molar ratio ranges from 90:10 to 70:30.
  Oligoclase is a high sodium feldspar crystallizing in the triclinic system. The Mohs hardness is 6 to 6.5 and the specific gravity is 2.64 to 2.66. The refractive indices are: nα=1.533–1.543, nβ=1.537–1.548, and nγ=1.542–1.552. In color it is usually white, with shades of grey, green, or red.
context_section_description: Oligoclase is a rock-forming mineral belonging to the plagioclase feldspars. In chemical composition and in its crystallographic and physical characters it is intermediate between albite (NaAlSi₃O₈) and anorthite (CaAl₂Si₂O₈). The albite:anorthite molar ratio ranges from 90:10 to 70:30.
  Oligoclase is a high sodium feldspar crystallizing in the triclinic system. The Mohs hardness is 6 to 6.5 and the specific gravity is 2.64 to 2.66. The refractive indices are: nα=1.533–1.543, nβ=1.537–1.548, and nγ=1.542–1.552. In color it is usually white, with shades of grey, green, or red.
caption: Oligoclase from Chihuahua, Mexico
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