SILVER
Silver
is part of the gold-group of metallic elements. Silver is a precious
metal, but is far less valuable than gold or platinum. Silver usually
occurs as a silver sulfide mineral, but it also occurs in nature in its native
state, often in the form of twisted wires.
Silver is moderately soft and has a silvery-white color on fresh
surfaces that tarnishes to darker colors. Elemental silver in nature is
often found alloyed with other metals. Naturally alloyed gold-silver is
called electrum.
Silver
wire (~3-5 mm sized masses) from the Mollie Gibson Mine near Aspen, central
Pitkin County, west-central Colorado, USA.
Silver
- large, tarnished silver wire mass from Kazakhstan (public display, Carnegie
Museum of Natural History, Pittsburgh, Pennsylvania, USA).
Silver
mass hosted in the Portage Lake Volcanic Series, from an unspecified locality
near Houghton, Keweenaw Peninsula, Michigan's Upper Peninsula, USA.
Silver mineralization occurred during the late Mesoproterzoic, at ~1.05-1.06
billion years. (Cranbrook Institute of
Science collection, Bloomfield Hills, Michigan, USA)
Silver
from Kongsberg, Norway. (Cranbrook Institute of Science collection,
Bloomfield Hills, Michigan, USA)
Silver
from Kongsberg, Norway. (Cranbrook Institute of Science collection,
Bloomfield Hills, Michigan, USA)
Silver
crystals ("herringbone silver") from the La Nevada Mine, Batopilas
District, Chihuahua State, northern Mexico (CSM 54598a & 54598b, Colorado
School of Mines Geology Museum, Golden, Colorado, USA).
Silver
from the Wolverine Mine, Houghton County, northern Upper Peninsula of Michigan,
USA. Silver at this locality crystallized ~1.05-1.06 billion years ago in
a pre-existing, ophitic basalt lava flow, the Kearsarge Flow (Portage Lake
Volcanic Series, upper Mesoproterozoic, 1.095 billion years). The
principal mining target at this mine (and at mines throughout the Keweenaw
Peninsula of northern Michigan) was copper.
Silver
(3.0 cm across at its widest) from the McKinley-Darragh Mine, southern side of
Cobalt Lake, Cobalt Mining District, southeastern Timiskaming District,
southeatern Ontario, southeastern Canada. Native silver at this mine
occurs in near-vertical hydrothermal veins consisting of
silver+cobalt-arsenides/sulfosalts+carbonate. The veins cut through
conglomerates, sandstones, and siltstones of the Coleman Member, Gowganda
Formation (Paleoproterozoic, 2.288 b.y.). Published literature on the
Cobalt Mining District has shown that the hydrothermal veins intruded through
their host rocks at about 2.217 billion years (~mid-Paleoproterozoic).
Hydrothermal vein mineralization appears to have been generated by, or related
to, intrusion of the Nipissing Diabase Sill, a widespread, 300 meter thick unit
in this area.