A cluster of microcline twinned crystals (10,0 x 9,5 cm) By Tom Epaminondas (mineral collector) and Eurico Zimbres (FGEL/UERJ) (Own work) [Public domain], via Wikimedia Commons
Microcline is a variety of feldspar. The only microcline you are likely to encounter is amazonite.
The International Gem Society (IGS) has a list of businesses offering
gemstone appraisal services.
Highest values go to color, transparency, size.
Microcline crystals, associated with smoky quartz, are popular mineral specimens from the Pike’s Peak area of Colorado. The color of amazonite ranges from pale green to dark green and blue-green. Pinkish orthoclase is also often present as an intergrowth.
Microcline is from Greek words meaning small and inclined because the cleavage is close to but not quite 90°.
Microcline occurs in acidic alkali-rich plutonic rocks; also in rocks such as pegmatites, granites, syenites, and schists.
- Pala, California; Maine: New York: North Carolina.
- USSR; Norway; Sweden: Germany; Italy; Japan: South Africa.
- Colorado (Pikes Peak area): amazonite.
- Amelia Courthouse. Virginia: finest amazonite in the United States.
- South Dakota: perthite.
- Canada: perthite, especially Ontario and Quebec.
- Brazil: fine amazonite.
- India (Kashmir District): amazonite.
- Australia (Harts Range).