Geode
Lapidary material
About it
A hollow, rounded rock lined inside with crystals, usually quartz, amethyst, or calcite. Keokuk geodes give Iowa its state rock; huge amethyst geodes come from Uruguay and Brazil.
- Type
- Lapidary material
- Group
- Hollow nodule
- Lustre
- vitreous (glassy), dull
- Colours
- grey or brown outside; quartz, amethyst, calcite, or agate inside
- Transparency
- opaque
Typical values: real specimens vary. For more, see mindat.org.