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ORTHOCLASE NATURAL COLOR Hardness 6 |
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17.45 cts. yellow orthoclase crystal single
14.2 x 12 mm.
This stone is transparent. Damage at the contact zone with its bed rock, but its shape is complete
Top crystal. Enhancement: none (N)
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stone PRICE
USD 104.00
ORIGIN: Itrongay, Madagascar
ref:Oyr1745
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22.59 cts. yellow orthoclase crystal single
16 x 16.4 mm.
This stone is transparent. Damage at the contact zone with its bed rock.
Top crystal. Enhancement: none (N)
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stone PRICE
USD 107.00
ORIGIN: Itrongay, Madagascar
ref:Oyr2259
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23.60 cts. yellow orthoclase crystal single
18.9 x 13.9 mm.
This stone is transparent. Damage at the contact zone with its bed rock, but its shape is complete.
Top crystal. Enhancement: none (N)
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stone PRICE
USD 125.00
ORIGIN: Itrongay, Madagascar
ref:Oyr2360
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32.82 cts. yellow orthoclase crystal single
23.5 x 18 mm.
This stone is transparent. Damage at the contact zone with its bed rock, damage at corners.
Top crystal. Enhancement: none (N)
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stone PRICE
USD 162.00
ORIGIN: Itrongay, Madagascar
ref:Oyr3282
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33.35 cts. yellow orthoclase crystal single
20.2 x 15.3 mm.
This stone is transparent. Damage at the contact zone with its bed rock, cleavage on a face.
Top crystal. Enhancement: none (N)
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stone PRICE
USD 196.00
ORIGIN: Itrongay, Madagascar
ref:Oyr3335
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37.50 cts. yellow orthoclase crystal single
22 x 18.7 x 9.1 mm.
Top crystal. Enhancement: none (N)
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stone PRICE
USD 299.00
ORIGIN: Itrongay, Madagascar
ref:Oyr3750
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42.08 cts. yellow orthoclase crystal single
18.1 x 18.5 x 14.5 mm.
Top crystal. Enhancement: none (N)
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stone PRICE
USD 234.00
ORIGIN: Itrongay, Madagascar
ref:Oyr4208
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44.52 cts. yellow orthoclase crystal single
23.4 x 19.1 x 11.4 mm.
Top crystal. Enhancement: none (N)
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stone PRICE
USD 296.00
ORIGIN: Itrongay, Madagascar
ref:Oyr4452
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44.84 cts. yellow orthoclase crystal single
20 x 19.3 x 12.4 mm.
Top crystal. Enhancement: none (N)
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stone PRICE
USD 338.00
ORIGIN: Itrongay, Madagascar
ref:Oyr4484
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66.08 cts. yellow orthoclase crystal single
26.9 x 21.8 x 17 mm.
Top crystal. Enhancement: none (N)
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stone PRICE
USD 438.00
ORIGIN: Itrongay, Madagascar
ref:Oyr6608
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Enlarge |
66.28 cts. yellow orthoclase crystal single
28.7 x 21.3 x 13.3 mm.
Top crystal. Enhancement: none (N)
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stone PRICE
USD 398.00
ORIGIN: Itrongay, Madagascar
ref:Oyr6628
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67.84 cts. yellow orthoclase crystal single
29 x 21.7 x 11 mm.
Top crystal. Enhancement: none (N)
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stone PRICE
USD 425.00
ORIGIN: Itrongay, Madagascar
ref:Oyr6784
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Enlarge |
79.89 cts. yellow orthoclase crystal single
30.5 x 30.1 mm.
Top crystal. Enhancement: none (N)
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stone PRICE
USD 480.00
ORIGIN: Itrongay, Madagascar
ref:Oyr7989
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79.74 cts. yellow orthoclase crystal single
29.2 x 22.7 x 17.4 mm.
Top crystal. Enhancement: none (N)
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stone PRICE
USD 680.00
ORIGIN: Itrongay, Madagascar
ref:Oyr7974
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84.06 cts. yellow orthoclase crystal single
33.2 x 20 x 16.5 mm.
Top crystal. Enhancement: none (N)
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stone PRICE
USD 680.00
ORIGIN: Itrongay, Madagascar
ref:Oyr8406
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84.85 cts. yellow orthoclase crystal single
20.7 x 22.8 x 17.5 mm.
Top crystal. Enhancement: none (N)
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stone PRICE
USD 668.00
ORIGIN: Itrongay, Madagascar
ref:Oyr8485
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100.35 cts. yellow orthoclase crystal single
34.4 x 30.6 x 20.1 mm.
Top crystal. Enhancement: none (N)
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stone PRICE
USD 785.00
ORIGIN: Itrongay, Madagascar
ref:Oyr10035
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102.92 cts. yellow orthoclase crystal single
41.1 x 24 x 15.7 mm.
Top crystal. Enhancement: none (N)
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stone PRICE
USD 995.00
ORIGIN: Itrongay, Madagascar
ref:Oyr10292
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24 grms. yellow orthoclase crystal single
39 x 21 x 16 mm.
Top crystal. Enhancement: none (N)
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stone PRICE
USD 1090.00
ORIGIN: Itrongay, Madagascar
ref:Oyr24g
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113.5 grms. yellow orthoclase crystal single
77.7 x 35.3 mm.
Top crystal. Enhancement: none (N)
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stone PRICE
SOLD
ORIGIN: Itrongay, Madagascar
ref:Oyr113.5gr
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60 grms. yellow orthoclase crystal single
50.6 x 28.2 mm.
Top crystal. Enhancement: none (N)
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stone PRICE
USD 2300.00
ORIGIN: Itrongay, Madagascar
ref:Oyr60gr
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55.50 grms. yellow orthoclase crystal single
47.2 x 29 mm.
Top crystal. Enhancement: none (N)
Enlarge
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stone PRICE
SOLD
ORIGIN: Itrongay, Madagascar
ref:Oyr5550g
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Enlarge |
25.80 grms. yellow orthoclase crystal single
31 x 25.2 mm.
Top crystal. Enhancement: none (N)
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stone PRICE
SOLD
ORIGIN: Itrongay, Madagascar
ref:Oyr2580g
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143 grms. yellow orthoclase crystal single
56 x 50.5 mm.
Top crystal. Enhancement: none (N)
Enlarge
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stone PRICE
USD 4800.00
ORIGIN: Itrongay, Madagascar
ref:Oyr14300g
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General Information
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Chemical Formula: |
KAlSi3O8 |
Composition: |
Molecular Weight = 278.33 gm |
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Potassium 14.05 % K 16.92 % K2O |
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Aluminium 9.69 % Al 18.32 % Al2O3 |
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Silicon 30.27 % Si 64.76 % SiO2 |
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Oxygen 45.99 % O |
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______ ______ |
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100.00 % 100.00 % = TOTAL OxIDE |
Empirical Formula: |
KAlSi3O8 |
Environment: |
Intrusive and extrusive igneous, and metamorphic rocks. |
IMA Status: |
Approved IMA 1960 |
Locality: |
Common world wide occurrences. Madagascar |
Name Origin: |
From the Greek orthos - "right" and kalo -" I cleave" in allusion to the mineral's right angle of good cleavage. |
Synonym: |
Adularia |
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Orthose |
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Orthoclase Images
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Faceted orthoclase |
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Click on the picture to go to faceted orthoclase |
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© Image by A. Darbellay |
Crystallography
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Axial Ratios: |
a:b:c =0.6636:1:0.5534 |
Cell Dimensions: |
a = 8.625, b = 12.996, c = 7.193, Z = 4; beta = 116.016ø V = 724.57 Den(Calc)= 2.55 |
Crystal System: |
Monoclinic-Prismatic H-M Symbol (2/m) Space Group: C2/m |
x Ray Diffraction: |
By Intensity(I/Io): 3.18(1)4.02(0.9) 3.8(0.8) |
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Physical Properties
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Cleavage: |
[001] Perfect, [010] Good |
Color: |
colorless, greenish, grayish yellow, white, or pink. |
Density: |
2.56 |
Diaphaniety: |
Transparent to translucent |
Fracture: |
Uneven - Flat surfaces (not cleavage) fractured in an uneven pattern. |
Habits: |
Prismatic - Crystals Shaped like Slender Prisms (e.g. tourmaline)., Massive - Granular - Common texture observed in granite and other igneous rock., Blocky - Crystal shape tends to be equant (e.g. feldspars). |
Hardness: |
6 - Orthoclase |
Luminescence: |
None. |
Luster: |
Vitreous (Glassy) |
Streak: |
white |
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Optical Properties
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Optical Data: |
Biaxial (-), a=1.518, b=1.522, g=1.523-1.524, bire=0.0050-0.0060, 2V(Calc)=52-70, 2V(Meas)=65-75. Dispersion relatively strong. |
Pleochroism (x): |
colorless. |
Pleochroism (y): |
colorless. |
Pleochroism (z): |
colorless. |
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Classification
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Dana Class: |
Tectosilicate Al-Si Framework |
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with Al-Si frameworks |
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(Na,Ba) feldspars |
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- Orthoclase KAlSi3O8 C2/m 2/m
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- Sanidine (K,Na)(Si,Al)4O8 C2/m 2/m
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- Hyalophane (K,Ba)Al(Si,Al)3O8 C2/m 2/m
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Celsian BaAl2Si2O8 I21/c 2/m |
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- Microcline KAlSi3O8 C1- -1
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- Anorthoclase (Na,K)AlSi3O8 C1- -1
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- Rubicline ! (Rb,K)AlSi3O8 P1- -1
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Strunz Class: |
Silicates |
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ectosilicates (network) without anions unfamiliar to the tetraheders |
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STRUNZ - Silicates [Tectosilicates (network) without anions unfamiliar to the tetraheders {Feldspar group, Buddingtonite - Orthocl |
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- Buddingtonite (NH4)AlSi3O8·0.5(H2O) P21 or P21/m Mono
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- Sanidine (K,Na)(Si,Al)4O8 C2/m 2/m
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Microcline KAlSi3O8 C1- -1 |
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- Orthoclase KAlSi3O8 C2/m 2/m
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- Celsian BaAl2Si2O8 I21/c 2/m
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- Hyalophane (K,Ba)Al(Si,Al)3O8 C2/m 2/m
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- Paraselsian BaAl2Si2O8 P21/c 2/m
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- Slawsonite (Sr,Ca)Al2Si2O8 P21/a 2/m
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