May 29, 2018 · Feldspar Feldspar is the most common mineral on Earth [1], constituting approximately 60% of the crust . It forms directly from cooling magma and is a major …

May 8, 2018 · feldspars The most important group of rock-forming silicate minerals, including the alkali feldspars KAlSi 3 O 8 to NaAlSi 3 O 8 (K-feldspar to albite) and the plagioclase feldspars …

May 8, 2018 · plagioclase feldspar One of the most important rock-forming silicate minerals with the general formula (Na,Ca) (Al) 1–2 (Si) 2–3 O 8. There is a solid solution series (see …

May 8, 2018 · Basalt Basalt is a mafic volcanic rock consisting primarily of plagioclase feldspar and pyroxene minerals . Common accessory minerals can include other pyroxenes, olivine , …

May 8, 2018 · alkali feldspar A group of silicate minerals that contain the alkali metal elements potassium and sodium. The normal feldspar minerals (including the calcium-bearing varieties) …

Mohs ’ Scale Mohs ’ scale, sometimes also called Mohs ’ hardness scale or Mohs ’ scale of mineral hardness, provides an index and relative measure of mineral hardness (i.e., resistance …

augen-gneiss A medium- to coarse-grained, banded, regional metamorphic rock composed mainly of quartz and feldspar with hornblende and mica also present in variable quantities, and …

adamellite A rock of granitic composition (see GRANITE) characterized by the presence of quartz, plagioclase feldspar, and potassic feldspar (see ALKALI FELDSPAR) accompanied by biotite …

May 29, 2018 · The most common sand is composed of particles of quartz and feldspar. Quartz sand particles are colorless or slightly pink, while feldspar sand has a pink or amber color. …

albitization The partial or complete replacement of pre-existing plagioclase feldspar or alkali feldspar by albite. There are a number of ways in which this can be achieved. Source for …