Septarian nodule
Rock
Also called Septarian and Dragon stone
About it
A concretion of hardened mud or clay ironstone, cracked inside, with the cracks filled by yellow or brown calcite. Cut and polished pieces from Utah and Madagascar show the pattern well.
- Type
- Rock (sedimentary)
- Group
- Sedimentary (concretion)
- Colours
- grey, brown, with yellow or brown calcite veins
- Transparency
- opaque
Typical values: real specimens vary. For more, see mindat.org.