[Rockhounds] Another extinction impact-13 KYA

[DonH]

Dora Smith wrote:
> OK, so lonsdaleite is hexagonal, and is similar to diamonds, but is not 
> actually a diamond.


Lonsdaleite is what would be called a polymorph of carbon--graphite, 
carbon nanotubes, and diamond are all arrangements of carbon.

> Wonder who invented that six sided diamond notion - the authors, who 
> seem flaky enough, or the media?

The information in my last post is still valid--in literal terms, a 
"six-sided diamond" would be a cubic (hexahedral) diamond.  However, 
Pete's introduction of lonsdaleite in the subsequent post brought some 
doubt about the terms being used; in other words, is the author 
referring to a relative of diamond with a hexagonal unit cell (i.e. 
lonsdaleite), and then translating that incorrectly as a "six-sided 
diamond?"  In today's environment of science-as-entertainment and 
science-as-politics, anything is possible.

However, there is no debate that lonsdaleite is NOT diamond, just as 
stishovite and coesite are NOT quartz.


Don