Microcline Value, Price, and Jewelry Information

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

Microcline is a variety of feldspar. The only microcline you are likely to encounter is amazonite.

Microcline Value

Highest values go to color, transparency, size.

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

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°.

FELDSPAR: Microcline-amazonite, Amelia Court House Virginia, (1inch); Canada (~2 inches across)

FELDSPAR: Microcline-amazonite, Amelia Court House Virginia, (1 inch); Canada (~2 inches across). Photo © Joel E. Arem, PhD, FGA. Used with permission.

Occurrence

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).
Amazonite

Amazonite

Enter your email to access the Ultimate Opal Buying Guide for free!

FREE

THANK YOU!

 

PLEASE CHECK YOUR EMAIL FOR THE E-BOOK

Follow us on Facebook