Microcline Value, Price, and Jewelry Information

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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.

Microcline Value

The International Gem Society (IGS) has a list of businesses offering gemstone appraisal services.

Highest values go to color, transparency, size.

Microcline Information

Data	Value
Name	Microcline
Is a Variety of	Feldspar
Varieties	Amazonite
Crystallography	Triclinic
Refractive Index	1.514-1.539
Colors	White, green, blue, pink, orange
Luster	Vitreous.
Polish Luster	Greasy to vitreous.
Fracture Luster	Pearly to vitreous.
Hardness	6-6.5
Wearability	Poor
Fracture	Uneven to splintery
Specific Gravity	2.54-2.58
Birefringence	0.007-0.010
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.
Heat Sensitivity	Yes
Luminescence	Yellow-green in LW; inert SW; green in X-ray
Luminescence Present	Yes
Luminescence Type	Fluorescent, UV-Long, X-ray Colors
Enhancements	Wax impregnation, hides fractures, common, moderately stable, detect with hot point. Irradiation, produces blue amazonite from white microcline, rare, stable, undetectable.
Typical Treatments	Fracture/Cavity Filling, Infusion/Impregnation, Irradiation
Transparency	Semitranslucent to opaque.
UV Long	Inert to weak yellowish green
UV Short	Inert
Absorption Spectrum	None distinct.
Phenomena	Aventurescence 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.)
Pleochroism	None.
Optics	α = 1.514-1.529; β = 1.518-1.533; γ = 1.521-1.539. Biaxial (-); 2V= 66-103°.
Optic Sign	Biaxial -

Comments

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.

Name

Microcline is from Greek words meaning small and inclined because the cleavage is close to but not quite 90°.

Occurrence

Microcline occurs in acidic alkali-rich plutonic rocks; also in rocks such as pegmatites, granites, syenites, and schists.