How can gold and pyrite be scratched to determined their hardness differences?

Answer 1

that is easy, if the sample is big enough to scratch. If it is only small flakes remember that gold will smear out but pyrites will crush in a brittle way. Pyrites will change colour as you heat them (propane torch, candle and tweezers?) because the sulfer burns off leaving iron oxide. Usually the difference is noticible between pyrites and gold without heating. Gold has a glow to it and pyrites have a hard glitter. Sometimes other metals are with the gold. Silver whitens gold and is called Electrum, red gold is usually copper in it. Mercury and arsenic are two toxic metals sometimes alloyed with gold too.
If you are panning the weight difference is a good clue. Pyrites are lighter . Mica flakes are very light but the colour can confuse some people. Remember again, Gold is soft and ductile, it will squish out or smear instead of crumbling or shattering. If you have a small torch (pencil or micro tip butane or propane)gold will melt to a glob of molten metal (do not inhale any fumes) while most other yellows change colour, burn or don't melt.

edit. If you are scratching, a pocketknife will cut gold, it will not cut pyrite. if you are crushing use a dark plate and a hard pestle (a sample pick hammer is fine)

Answer 2

Hardness Of Pyrite

Answer 3

Pyrite Hardness

Answer 4

Gold has a low hardness of 3, while that of pyrite is 6-6.5 (almost as hard as a glass plate). You can use a brass plate (hardness 5). Since gold is softer that brass, the brass plate will not show any scratch. But pyrite will scratch a brass plate very easily. A copper coin can also be used.

Answer 5

True gold is much softer than iron pyrite (fools gold.) And when seen side by side, are quite difference in appearance.
One simple test the 49'ers used was to bite into it; if it dented, it was likely to be gold.

Answer 6

Use a hardness tester. Gold is about 2.5 - 3.0 on the Moh's scale. Pyrite is about 6.5.