Mother Lode Gold Ore (above & below) - these are samples of hydrothermal quartz-gold veins from California, USA. This gold occurrence is part of the Mother Lode Gold Belt in the Sierra Nevada foothills.  The Au-quartz mineralization occurred during the late Early Cretaceous, at about 108-127 million years ago, in the Melones Fault Zone (= the boundary between the Foothills Terrane and the Don Pedro Terrane).  To the east of the fault zone is Jurassic slate.  To the west of the fault zone is a Jurassic serpentinite melange.  The Melones Fault Zone was active principally in the late Jurassic and early Cretaceous.

Above: quartz-gold vein sample (3.2 cm across) from the Harvard Open Pit Mine, northwestern side of Rt. 49/Rt. 108, western side of Woods Creek, just west of Jamestown, western Tuolumne County, central California, USA.  37 56' 50" North , 120 36' 20" West.

Below: quartz-gold vein sample from an unspecified mine at or near Grass Valley, Nevada County, northeast-central California, USA.  (Cranbrook Institute of Science specimen, Bloomfield Hills, Michigan, USA)

Mother Lode Gold Ore



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