Allanite
| Refractive Index : 1.828 – 1.640 |
| Optical Characteristic : DR B- |
| Specific Gravity : 4.20 – 3.40 |
| Formula : (Y,Ce,Ca) 2 (Al,Fe+++) 3 (SiO4) 3 (OH) |
| Crystal System : Monoclinic |
| Variety/Species : Allanite |
| Species/Group : Epidote Groupy |
| Birefringence : 0.019 to 0.045 |
| Dispersion : 0.030 |
| Hardness : 6 to 7 |
| Toughness : Fair to poor |
| Ultrasonic : Risky |
| Steam : Never |
| UV Long : Inert |
| UV Short : Inert |
| Pleochroism : 3 Colors |
| Strength : Moderate |
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| Pleochroism Colors : Press the |
| Heat : Fusible |
| Acids : Attacked by acids and /or chemicals |
| Light : Stable |
| Polish Luster : Vitreous to greasy |
| Fracture : Uneven to conchoidal |
| Fracture Luster : Resinous |
| Clarity Type : N/A |
| Tones : N/A |
| Saturations : N/A |
| Cause of Color : |
| Enhancements : None |
| Cleavage : Perfect in 1 direction |
| Color Range : Brown, light brown, black Brownish, blackish |
| Transparency : Transparent to Translucent |
| Phenomena : None |
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| Separations : Allanite from- Kyanite: spectrum, pleochroism, color birefringence, cleavage Idocrase: spectrum, optic character birefingence, cleavage Zoisite: birefringence, spectrum, color, RI, pleochroism |
| Identifying Characteristics and information None. Use a combination of properties. May show pseudo-uniaxial optic figure. Allanite is part of the Epidote group which also includes Zoisite, Clinozoisite, Hancockite and Piedmontite. Allanite is weakly radioactive. |
| Spectral Data Not Diagnostic. |
| Trade Names and Misnomers Allanite Orthite |
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