PLATINUM
Platinum (Pt) is far more valuable that gold, but it
doesn't have a distinctive, prestigious color. Like most metals, platinum
has a silvery color. Platinum, when purified, is heavier than gold, but
specimen platinum has about the same specific gravity as gold nuggets (about
19).
Platinum is alway found significantly alloyed with
other elements, usually other PGEs (platinum-group elements: platinum
(Pt), palladium (Pd), osmium (Os), iridium (Ir), rhenium (Re), rhodium (Rh),
ruthenium (Ru)). Platinum is typically found in Precambrian ultramafic
igneous rocks, but there are also some Pt-bearing placer deposits in Canada,
Colombia, and Russia.
Platinum
nuggets (~1 to 2 mm in size) from a placer deposit in Granite Creek, a
tributary of the Tulameen River near Granite City, a ghost town in southern
British Columbia, southwestern Canada.
This was a significant platinum occurrence. It's
been reported that >20,000 ounces worth of platinum nuggets were recovered
from this area from the mid-1880s to the mid-1930s.
Granite Creek platinum nuggets are derived from
weathering of PGE-bearing chromitic dunites in the Tulameen Ultramafic
Complex of Early Jurassic age.
Available assay information indicates that Granite
Creek nuggets are 68 to 78% platinum (Pt), 4 to 14% osmiridium (Ir,Os), 8 to
10% iron (Fe), 3 to 4% copper (Cu), 3% rhodium (Rh), 1% iridium (Ir), and 0.2%
palladium (Pd).
Platinum
mass & well-formed crystals from Russia.