James St. John:
Obsidian 1
James St. John:
Obsidian 9
James St. John:
Obsidian 14
James St. John:
Obsidian 20
James St. John:
Obsidian 26
James St. John:
Gray obsidian 4
James St. John:
Shungite (Zaonezhskaya Formation, middle Paleoproterozoic, 1.98-2.09 Ga; Shun'ga River area, northwestern Russia) 13
James St. John:
Obsidian 32
James St. John:
Mahogany obsidian (Tertiary, 5.03-7.7 Ma; Glass Buttes, Oregon, USA) 2
James St. John:
Conchoidally-fractured quartz 1
James St. John:
Conchoidally-fractured quartz 2
James St. John:
Conchoidally-fractured quartz 3
James St. John:
Conchoidally-fractured quartz 4
James St. John:
Rose quartz 2
James St. John:
Rose quartz 3
James St. John:
Shungite (Zaonezhskaya Formation, middle Paleoproterozoic, 1.98-2.09 Ga; Shun'ga River area, northwestern Russia) 7
James St. John:
Common opal (Nevada, USA) 17
James St. John:
Golden-sheen obsidian (Mexico) 8
James St. John:
Golden-sheen obsidian (Mexico) 6