Cause of Color :
Rose Quartz: Charge transfer reaction (Ti4+
) as a result of irradiation.
Chemical Composition :
Silica (Silicon Dioxide) SiO2
Crystal System / Forms :
- Prismatic with pyramidal terminations (rhombohedron, trapezohedron, trigonal, pyramid)
- Horizontal striations on the prism face, rhomb shaped on rhombohedral face, ‘V’ shaped markings in twinned crystals.
- Most quartz is commonly twinned.
- Types of twinning include Dauphine, Brazil and Japan law twinning.
- Exhibits both contact and interpenetrant twinning.
Cuts & Uses :
Facetted cuts, cabochon, carvings, beads, etc.
Liquid and two phase, color zoning, negative crystals, zebra-stripe finger prints (structural), crystal inclusions, green fuchsite mica flakes / platelets in aventurine quartz, rutile / tourmaline needles in sagenitic quartz. Brazil law twinning is seen in natural quartz.
Optic Character :
Anisotropic, D.R.; Uniaxial positive. May exhibit a bull’s eye optic figure (quartz rotates the plane of polarisation parallel to the c-axis).
Dichroism - weak to moderate.
Refractive Index / Birefringence :
1.544 – 1.553 / 0.009. Range: 1.535 – 1.560
Brazil, India, South Africa, Namibia, Madagascar, Zambia, Sri Lanka.
Specific Tests :
- Piezoelectric: develops an electric charge when pressure is applied.
- Pyroelectricity: develops an electrical charge when heated.
- Diasterism in star variety (star visible in reflected and transmitted light).
Green aventurine: bands at 682nm, 649nm
- Colors – colorless, pink, blue, green, etc.
- Identification: type of twinning, seed plate, breadcrumb inclusions, Raman / infra-red spectroscopy.