Oligoclase is a rock-forming mineral belonging to the plagioclase feldspars. In thin section, plagioclase feldspar grains often look like they’re sprinkled with dirt (PPL) or tiny confetti (XPL). Albite and Anorthite are the end members of the series, with the intermediary minerals Oligoclase, Andesine, Labradorite, and Bytownite. Chemical Formula: Oligoclase is a mid-composition plagioclase feldspar Oligoclase ranges from 90% to 70% NaAlSi 3 O 8 and 70% to 50% CaAl 2 Si 2 O 8. In chemical composition and in its crystallographic and physical characters it is intermediate between albite (Na Al Si 3 O 8) and anorthite (CaAl 2 Si 2 O 8). Albite is the sodium-rich end member while Anorthite is the You can find the explanation on the plagioclase feldspar page. General Plagioclase Information : Chemical Formula: (Na,Ca)(Si,Al)4O8 : Composition: Molecular Weight = 270.77 gm Sodium 4.25 % Na 5.72 % Na 2 O: Calcium 7.40 % Ca 10.36 % CaO: Aluminum 9.96 % Al 18.83 % Al 2 O 3: Silicon 31.12 % Si 66.57 % SiO 2: Oxygen 47.27 % O: 100.00 % 101.48 % = TOTAL OXIDE Chemical Composition: Ranges from NaAlSi 3 O 8 (Albite) to CaAl 2 Si 2 O 8 (Anorthite) Color: Typically white to gray, may also range from colorless, through shades of off-white, to yellowish, pink, reddish brown or nearly black. Oligoclase is a plagioclase feldspar, intermediate between albite and anorthite.. Franklin, Franklin Mining District, Sussex Co., New Jersey, USA (yellow LW); Mitchell Co., North Carolina, USA (dim brownish-white LW); (*)Data are not exhaustive and … Plagioclase is a continuous series of solid solutions known as the plagioclase feldspar series, rather than a specific mineral with a particular chemical composition. The Plagioclase Feldspars form a series between Albite and Anorthite. Oligoclase is a somewhat rare variety of Albite and a member of the Plagioclase Feldspars of the Feldspar Group of minerals that includes Albite, Amazonite, Andesine, Anorthite, Bytownite, Hyalophane, Labradorite, Moonstone,Oligoclase, Orthoclase, Sanidine and Sunstone. The Plagioclase Feldspars form a series between Albite and Anorthite. The albite:anorthite molar ratio of oligoclase ranges from 90:10 to 70:30. Oligoclase is a somewhat rare variety of Albite and a member of the Plagioclase Feldspars of the Feldspar Group of minerals that includes Albite, Amazonite, Andesine, Anorthite, Bytownite, Hyalophane, Labradorite, Moonstone, Oligoclase, Orthoclase, Sanidine and Sunstone. Physical Properties of Sunstone: Chemical Formula: Microcline: KAlSi 3 O 8 Oligoclase: (Na,Ca)Al 1-2 Si 3-2 O 8: Chemical Composition: Crystal System: Triclinic: Lustre: Vitreous The Plagioclase series is a group of related feldspar minerals that essentially have the same formula but vary in their percentage of sodium and calcium.
2020 oligoclase chemical formula