11. It occurs in a quartz vein within a diabase -porphyry shear zone. 12. Once an active volcano, the diabase mountain was formed 160 million years ago. 13. These particular ringing rock boulder fields formed from a rock type called olivine diabase . 14. Both the normal and olivine diabase rocks are dark grey to black in color. 15. The diabase on V�stg�tabergen known locally for staircases. 16. The ridge consists largely of diabase , much like its sister formation East Rock. 17. In 1990 Widenfalk had acquired a small diabase block of highest quality and blackness. 18. Skansen has 4-5 metre thick walls made of granite, gneiss and diabase . 19. Farming use was limited due to the hard diabase rock in the mountain s soil. 20. The Australian occurrences include a number of Proterozoic to Cambrian age diabase and gabbro sills.
