DATOLITE
Datolite is a calcium hydroxy-borosilicate mineral
(CaB(SiO4)(OH)). It has a glassy, nonmetallic luster, is
typically clear to white to light green in color, has a white streak, is
moderately hard (H=5), and has no cleavage. It is typically encountered
as a vug-filling mineral in ancient basalt lava flows.
Datolite
crystals (6.5 cm across) from Newington, Connecticut, USA that partially filled
a cavity in Triassic rift basin basalts.
Datolite nodule (cut & polished interior) from the Centennial
Mine in Houghton County, Upper Peninsula (UP) of Michigan, USA. Datolite
nodules of this size occur in a mulitutude of colors in the UP of
Michigan. It is the only area on Earth that has such a datolite
occurrence. These fracture-filling nodules are hosted in the Portage Lake
Volcanic Series and formed during the late Mesoproterozoic, at 1.05-1.06
billion years. (Seaman Mineral Museum specimen, Michigan Technological
University, Houghton, Michigan, USA)
Datolite nodule (cut & polished interior) from the Caledonia
Mine, Ontonagon County, UP of Michigan, USA. (Seaman Mineral Museum
specimen, Michigan Technological University, Houghton, Michigan, USA)
Datolite nodule from the Clark Mine, Keweenaw County, UP of Michigan,
USA. (Seaman Mineral Museum specimen, Michigan Technological University,
Houghton, Michigan, USA)
Datolite nodule from the Quincy Mine, Houghton County, UP of
Michigan, USA. (Seaman Mineral Museum specimen, Michigan Technological
University, Houghton, Michigan, USA)
Datolite nodule from the Adventure Mine, Ontonagon County, UP of
Michigan, USA. (Seaman Mineral Museum specimen, Michigan Technological
University, Houghton, Michigan, USA)
Datolite nodule (mixed with native copper) from the Quincy Mine,
Houghton County, UP of Michigan, USA. (Seaman Mineral Museum specimen,
Michigan Technological University, Houghton, Michigan, USA)