How can you tell if a rock has gold or fool's gold?

Pyrite forms cube-shaped crystals and smells of sulphur when crushed. Weathered mica flakes look gold in the sun but are light, flaky and float in a pan. Gold is so heavy that it stays at the bottom of the pan.

For gold you cannot see, only an assay laboratory can tell you how much a rock contains.

Sources: Mineral identification standards (streak, hardness, malleability).

What rock is most likely to have gold in it? Quartz is the rock most often associated with gold: most lode gold occurs in quartz veins, especially rusty, iron-stained quartz near faults. Gold is also found in the contact zones between granite-type intrusions and older metamorphic rocks such as schist and greenstone.

What does raw gold look like? Raw gold is a buttery, warm yellow that does not glitter or flash; it looks the same in sun and shade. Placer gold comes as flat flakes, fine dust and rounded nuggets. Gold still in rock appears as specks, wires or seams, usually in quartz.