Microcline (KAlSi₃O₈) is a triclinic potassium feldspar and the parent species of one of the most prized collector varieties — amazonite, the vivid blue-green form colored by trace lead and water content. Microcline forms in granitic pegmatites and high-grade metamorphic rocks; classic Pikes Peak (Colorado) and Madagascar deposits supply gem-grade amazonite.
Key Facts
- Mohs hardness 6–6.5.
- Triclinic; cross-hatched “tartan” twinning is diagnostic in thin section.
- Amazonite variety = blue-green color from Pb²⁺ + structural water.
- Forms a continuous solid-solution series with albite (Na endmember).
- Major rock-forming mineral in granites and pegmatites.
Notable Localities
Pikes Peak (Colorado, USA) and Madagascar produce world-class amazonite. Russia’s Ural Mountains and Brazil’s Minas Gerais yield additional collector material.
Found at these Localities
- Eastern Brazilian Pegmatite Province (巴西东部伟晶岩省)
