GEMSTONE LIBRARY
AMETHYST
CHARACTERISTICS
- Name: Amethyst
- Mineralogical nature: Quartz
- Colour: Purple
- Crystal system: Rhombohedral
- Chemical composition: SiO2
- Causes of colour: O2- – Fe4+
- Physical properties:
- Density: 2.65
- Hardness: 7
- Cleavage: None
- Fracture: Conchoidal
- Optic sign: Positive uniaxial
- Refractive index: no: 1.538 to 1.544 / ne: 1.547 to 1.553
- Birefringence: 0.009
- Dispersion: 0.013
- Pleochroism: Purple – purple to violet – blue
- UVL: Inert
- UVC: Inert
- Treatments: Irradiation
- Syntheses: Hydrothermal Dissolution
- Geographical origin: Uruguay, Brazil, Bolivia, Zambia, Morocco, Nigeria, Russia, Madagascar, etc.