What is the green microcline called?
Microcline is one of the most common minerals of the feldspar family and is part of the potassium feldspar group. Polymorphic with orthoclase, sanidine, kokchetavit.
Mineral varieties
Amazonite is a green variety of the mineral microcline.
Special Properties
The microcline mineral usually contains intergrowths of albite (perthite). Behavior in acids: insoluble. Microcline is one of the main rock-forming minerals of granites, granodiorites, syenites, granite pegmatites, hydrothermal and metamorphic rocks (crystalline schists, gneisses).
Place of Birth
The largest microcline deposits are located in Germany, Switzerland, Kazakhstan, Norway, Poland, USA, Ukraine, Japan and Madagascar. Large deposits of the microcline mineral in Russia are located in the Urals, Karelia, and the Kola Peninsula (amazonite is a type of microcline).
Application
The microcline mineral is an important raw material for the ceramic industry; it is used in the production of technical ceramics, porcelain, and earthenware. A variety of microcline, amazonite, is used as an ornamental stone.
Properties of the Mineral
| Color | colorless, white, gray, grayish-yellow, yellowish, tan, salmon pink, brownish-red, bluish-green, green, sometimes iridescent |
| Line color | white |
| Origin of the name | From the Greek micro – small and wedge – angle, since the cleavage angle of a microcline differs from a right angle by only 20′ |
| Opening place | Arendal, Aust-Agder, Norway Stavern (Fredriksvärn), Larvik, Vestfold, Norway |
| Opening year | 1830 |
| IMA status | valid, first described before 1959 (before IMA) |
| Chemical formula | K[AlSi3O8] |
| Brilliance | glass |
| Transparency | transparent translucent shines through |
| Cleavage | perfect by perfect by |
| Kink | uneven |
| Hardness | 6 6,5 |
| Thermal properties | P. tr. melts with difficulty |
| Typical impurities | Fe,Ca,Na,Li,Cs,Rb,H2O,Pb |
| Strunz (8th edition) | 8/J.06-30 |
| Hey’s CIM Ref. | 16.3.5 |
| Dana (8th edition) | 76.1.1.5 |
| Molecular weight | 278.33 |
| Cell Options | a = 8.5784Å, b = 12.96Å, c = 7.2112Å α = 90.3°, β = 116.05°, γ = 89° |
| Attitude | a:b:c = 0.662 : 1 : 0.556 |
| Number of formula units (Z) | 4 |
| Unit cell volume | V 720.16 ų |
| Twinning | Carlsbad, Baven, polysynthetic twins. Characteristic are intersecting polysynthetic systems. dv. according to the albite and pericline laws, forming the so-called. micro wedge grid |
| Point group | 1 – Pinacoidal |
| Space group | C / 1 |
| separateness | By , , , |
| Radioactivity (GRapi) | 200.97 |
| Density (calculated) | 2.56 |
| Density (measured) | 2.54 – 2.57 |
| Optical axis dispersion | r > v weak |
| Refractive indices | nα = 1.514 – 1.529 nβ = 1.518 – 1.533 nγ = 1.521 – 1.539 |
| Maximum birefringence | δ = 0.007 – 0.010 |
| Type | biaxial (-) |
| angle 2V | measured: 66° to 103°, calculated: 80° |
| Optical relief | low |
| Selection form | short-prismatic or tabular crystals, often of considerable size, granular masses, phenocrysts, ovoids; graphic intergrowths with quartz |
| Classes on taxonomy of the USSR | Silicates |
| IMA classes | Silicates |
| Syngonia | triclinic |
| fragility | Yes |
| Irisation | Yes |
| Literature | Allan, DR & RJ Angel (1997), A high-pressure structural study of microcline (KAlSi3O8) to 7 GPa: European Journal of Mineralogy: 9: 263-275. |
No. 1-210. Mokrusha, Murzinka, Wed. Ural. 3,7 x 3,2 x 2,4 cm 
| Formula: KAlSi 3 O 8 . |
| Class: Silicates |
| Group: Feldspars |
| Application: jewelry stone |
| Investment name: Microcline (PSh mineral) without amazonite |
Features
| Hardness (Mohs Scale) | 6,0-6,5 |
|---|---|
| Density | 2,54-2,63 *2,56 |
| Refraction | 1,518-1,534 * 1,53 |
| Birefringence | 0,07-0,010 |
| Variance | 0,012 |
| Color | White, green, bluish-green, light blue, blue, gray, yellow, pink, beige, red. |
| Transparency | Translucent to opaque. |
| Forms of selection | Columnar crystals, granular aggregates, blocks, inclusions. |
| Syngonia | Triclinic. |
| Cleavage | Perfect by (001) and (010). |
| Kink | Uneven, stepped. |
| double refraction | White. |
| Pleochroism | Absent. |
| Absorption spectrum lines | Not diagnosed. |
| Luminescence and Chelsea filter | Absent, sometimes slightly yellowish-green (LW), absent (SW.). |
| Characteristics | Feldspar. Characterized by mottled coloration, often with a shimmering effect. A microcline lattice can often be observed. The main jewelry varieties are amazonite and sunstone. |
| Field | Russia (Urals, Kola Peninsula, Karelia, Azov region), Kazakhstan, Canada, Zimbabwe, Brazil, Mozambique, USA (Arkansas, Colorado), Switzerland, Madagascar, Japan, Germany, Norway, Poland, etc. |
| Brilliance | Glassy to pearlescent and silky. |
More about microcline
Microcline is a polymorphic modification of feldspar group minerals. Named from the Greek words “micro” – small and “wedge” – tilt (the angle between the cleavage planes deviates from a straight line by 20°). If it is not possible to accurately identify a sample in the field, it is classified as a potassium feldspar (KFS). Other representatives of KPS include sanidine and orthoclase. The difference between these minerals is determined by more precise methods, but microcline is most often more intensely colored, cleavage is clearly visible in it, and it is the only one (although not always) that forms dark green secretions (amazonite). Microcline is a common, but not very well-known mineral in jewelry. Varieties of microcline are used in jewelry – amazonite, sunstone. Amazonite is a blue, bluish-green, dark green variety of microcline, suitable for polishing and cameo production. The colored stripes represent microcline, and the white stripes represent plagioclase. If plagioclase is absent, then such a microcline is called antiperthite. Twinning is characteristic of all feldspars. Twins are formed according to albite, pericline, Carlsbach and other laws. However, twinning according to the albite and pericline laws is more typical for plagioclases, but not for microcline. Well formed microcline crystals can be really interesting. In some deposits, amazonite forms intergrowths with smoky quartz, which has already become a classic collection specimen.
Market prices* for inserts, raw materials and collection stones (in USD) (*indicative)
| Faceted inserts (per 1 carat) | Gold price ratio | |||
|---|---|---|---|---|
| 1 carat or less | 3-5 carats | 10 carats or more | ||
| In Russia | virtually absent | virtually absent | virtually absent | —— |
| Abroad | proposed. unknown | proposed. unknown | proposals unknown | —— |
| For 1 g of raw materials | Crystals | Shufts | Rarely available for sale | |
|---|---|---|---|---|
| In Russia | not commonly used | 3 – 50 | 10 – 200 | rel.rare (not amazonite) |
| Abroad | 2 – 3 $/kg | 45 (Int) | 120 (Int) | collection stone |
