olivine & diamondsre "PETROGRAPHIC ROCK INDENTIFICATION OF SELECTED VICTORY DRILL CORES
CONFIRMS KIMBERLITE AND OLIVINE MELILITITE"
I knew I'd heard of this stuff before...
https://en.wikipedia.org/wiki/Argyle_diamond_mine
"The mine is the first commercial diamond mine (except alluvial mining operations) not located on a kimberlite pipe. The pipe is named "AK-1", although it is commonly simply called the "Argyle pipe".
The volcanic pipe is a diatreme, composed of olivine lamproite, present as tuff and lava."
"The Argyle diamond mine leads the world in volume production of diamond, averaging annual production of 35 million carats (7,000 kg), or about one third of global production of natural diamonds."