Check the listing for details. #OM-166 Crystalline Gold Nugget Specimen 1.11 Grams Oriental Mine Sierra County. Listed at 201.91 USD. Crystalline gold is the rarest and most beautiful form of natural gold. Gold found in California is often in quartz, which is typically a hard rock, mined in vertical or horizontal shafts. This contrasts with placer (loose gold, often nuggets) and fine gold that has been recovered by hydraulic mining.