Amethyst
Variety SiO2
Also called Purple quartz
Take care.
- Fades or changes in light: Keep it in the dark, out of sunlight and bright display lights.
- Sensitive to heat: Keep it away from heat and sudden changes of temperature, including hot lights and ultrasonic cleaners.
About it
Purple quartz coloured by iron and natural radiation; heating turns it yellow, and some pale stones fade in strong sun. Big geodes come from Brazil and Uruguay, and fine crystals from Zambia, Mexico, and Ontario.
- Type
- Variety
- Group
- Quartz variety
- Formula
- SiO2
- Hardness (Mohs)
- 7
- Specific gravity
- 2.65–2.66
- Streak
- white
- Lustre
- vitreous (glassy)
- Crystal system
- Trigonal
- Colours
- purple, violet, lilac, reddish purple
- Transparency
- transparent, translucent
- Cleavage and fracture
- none; conchoidal fracture
Typical values: real specimens vary. For more, see mindat.org.