Lonsdaleite
A hexagonal form of diamond made by shock, first found in the Canyon Diablo meteorite.
Key facts
- Formula
- C
- Family
- Carbon minerals
- Crystal system
- Hexagonal
- First described
- the Canyon Diablo iron meteorite, 1967
Lonsdaleite was described in 1967 from the Canyon Diablo meteorite that made Meteor Crater in Arizona. It is named after Kathleen Lonsdale, the Irish-born crystallographer who was one of the first two women elected Fellows of the Royal Society.
What it is
Lonsdaleite is carbon with a diamond-like bonding arrangement stacked in a hexagonal rather than cubic pattern. It forms when graphite is struck by a powerful shock. Some scientists argue that it is not truly a separate mineral but diamond full of stacking faults; others have reported larger, well-formed domains of it.
Where it is found
It occurs in shocked graphite in Canyon Diablo fragments, in ureilites, and at impact craters such as the Popigai structure in Siberia.
How it is recognised
It is identified by X-ray or electron diffraction, which shows a hexagonal pattern mixed with that of ordinary diamond.
Did you know?
Kathleen Lonsdale proved in 1929 that the benzene ring is flat.
Some calculations suggest that perfect lonsdaleite could be even harder than diamond.