Fulgurite
Rock
Also called Petrified lightning and Lightning glass
Take care.
- Fragile: Handle it gently and pack it well; it breaks or crumbles easily.
About it
Hollow, branching tube of glass formed when lightning melts sand or rock: rough and sandy outside, smooth and glassy inside. Found in dunes and beaches, notably in Florida and the Sahara, and as glassy crusts on mountain summits.
- Type
- Rock (metamorphic)
- Group
- Natural glass (lightning-fused)
- Lustre
- vitreous (glassy), dull
- Colours
- tan, grey, white, black, glassy inside
- Transparency
- translucent, opaque
Typical values: real specimens vary. For more, see mindat.org.