Geology, Palaeontology & Archaeology / Re: Which rocks contain metallic flakes resembling silver and gold?« on: 11/09/2017 05:16:33 »
Agreed with glot, they are probably mica flakes. Its fairly common to find them in layers or crusts in conglomerate rocks. A picture would help a whole bunch. You can also identify mica via simple hardness test. Mica forms in lamellae; thin, flexible sheets so you can easily separate it at just the right spot with a fingernail, pick or small knife. It also crushes or breaks rather easily compared to the other minerals in the host rock.
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