Chalcedony (microcrystalline quartz)
Agate
Agate's banding is a record of deposition: silica-rich fluid entered a cavity in volcanic rock and laid down layer after layer of fine-grained chalcedony against the cavity wall, each layer differing slightly in trace content and grain size. No two slices repeat.
- Mineral family
Chalcedony (microcrystalline quartz)
- Typical colours
Banded creams, greys, warm browns and rust reds
- Hardness (Mohs)
6.5 - 7
- Luster
Waxy to dull, vitreous when polished
- Texture
Dense and even, with sharply drawn parallel or concentric bands that read as ridges to the eye but polish perfectly flat.
Caring for it
Tough and suitable for everyday wear. Wash in cool soapy water, dry with a soft cloth, and avoid harsh chemicals and strong heat, which can dull the polish and affect the colour of some bands.