Microcline is a variety of feldspar. The only microcline you are likely to encounter is amazonite.
Highest values go to color, transparency, size.
The International Gem Society (IGS) has a list of businesses offering gemstone appraisal services.
|Is a Variety of||Feldspar|
|Refractive Index||1.518 - 1.534|
|Colors||White green blue pink orange|
|Polish Luster||Greasy to vitreous|
|Fracture Luster||Pearly to vitreous|
|Fracture||Uneven to splintery|
|Hardness||6 - 6.5|
|Specific Gravity||2.54 - 2.58|
|Cleavage||Perfect and easy in two directions|
|Stone Sizes||Amazonite cabochons up to almost any size are available; the material is usually sold by the pound to hobbyists. The same applies to perthite. The Amelia material has fine color and translucency, but perfect cleavage adds fragility.|
|Enhancements||Wax impregnation, hides fractures, common, moderately stable, detect with hot point. Irradiation, produces blue amazonite from white microcline, rare, stable, undetectable.|
|Transparency||Semitranslucent to opaque|
|UV Long||Inert to weak yellowish green|
|Phenomena||Adventurescence in amazonite|
|Identifying Characteristics||Mottled coloring with grid like patterns|
|Formula||KAlSi3O8 (Note, this is the same formula as orthoclase, but a different crystal system.)|
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).