Placer
Gold - Flattened nuggets of native gold found in Lynx Creek, Arizona. The
high degree of malleability of gold allows the grains to survive transport in
mountain streams at the expense of being flattened by large rocks.
Crystalline Gold
Gold in a vein of quartz
A close up view of the Gold in
quartz from the above picture.
This is a chunk of "gold
ore". It is milky quartz with inclusions of hematite and limonite.
The gold is not normally visible in this type of a rock. In this specimen
however, the gold is seen along the top edge and center of the rock. A
prospector would recognize the association of gold in this color of quartz.
The next step would be to pulverize the rock and then pan the debris to look for
the gold.
CHEMISTRY Au Gold
CRYSTALLOGRAPHY Isometric (Cubic)
CRYSTAL GROWTH AND HABITS Native gold occurs as octahedrons, dodecahedrons and cubes. It also forms wires, dendritic and spongy masses and as rounded nuggets and flakes.
COLOR AND OTHER OPTICAL PROPERTIES Gold is golden yellow when pure but silver lightens its color and copper tends to make it redder. It is opaque.
HARDNESS 2.5 - 3
SPECIFIC GRAVITY 19.3
LUSTER Bright metallic gold
STREAK Gold
BREAKABILITY Hackly fracture, very malleable, ductile and sectile
OCCURRENCE Gold is typically found in quartz veins or with pyrite and other sulfides. It is often concentrated in streams as placer deposits.
ASSOCIATED MINERALS Pyrite, Chalcopyrite, Quartz, Arsenopyrite, Silver