A prospector may find tiny quantities of gold inside igneous rocks. Some patches of such rocks contain concentrations of gold high enough to mine the ore and crush it to extract the gold. At first glance, the gold may not be visible in the ore.
अशा ठिकाणी वरवर पाहता खडकांमध्ये मोठ्या प्रमाणात सोनं उपलब्ध आहे हे कदाचित लगेच कळून येणार नाही.