After you have seen enough of the real stuff, gold, it gets easier to discriminate against the not so real stuff, fool's gold. But it is not unusual for a beginner to wonder about the difference between gold and other minerals found in the stream bed or lode deposits. Sometimes a beginner will be puzzled over shiny rocks and quite often iron pyrite better known as fool's gold. There is a story about an entire shipment of iron pyrite having been sent to England in the 1500's. You could imagine the dismay when it was finally discovered that it was just fool's gold.
Gold is a brassy yellow metal.
Gold does not look anything like rock. It looks like metal, gold metal. If you were just starting and have not yet had the opportunity to see much gold in its natural form there are some easy tests which will validate your discovery one way or another. Glitter Test, gold does not glitter, it shines. Sometimes its bright, sometimes it's dull, but very seldom does it glitter.