Crystal system: Cubic (crystals are rare, gold
mostly occurring in leaf, nugget or dendritic
Hardness: 2.5 to 3.
Colour: Yellow (the presence of silver makes gold more white, copper makes it more red)
Streak: Shiny yellow
A complete solid solution exists between gold and silver so that pure gold is extremely rare. The silver content is typically 2% to 20%. Gold also naturally alloys with copper. It is extremely malleable and can be hammered out into thin plates that are used for decoration. Gold occurs in quartz veins associated with silicon rich igneous rocks.
The specimen shown is leaf gold on quartz from Placer County, California.