In nature, only a few elements occur in their native form as a single, solid element, not chemically combined with others. Gold, the best known example, is less chemically active than most other elements that exist in solid form. Gold occurs as tiny particles in rocks; as hot water seeps through bedrock, it may carry the gold bits until they accumulate into small nuggets. A few other metals, such as silver and copper, are sometimes found in small standalone amounts in nature. Whether silver, copper, and platinum combine with other elements or remain as native elements depends on their proximity to other chemically active substances. A few nonmetallic elements also may occur in native form. For example, plain sulfur collects around the vents of hot springs and volcanoes, as well as in sedimentary structures like salt domes. In nature, carbon can appear in two different native forms, graphite and diamond, depending on how much heat and pressure have been applied to it.
- Catalog Number:
- 41492
- Specimen Count:
- 2
- Locality:
- Mexico
- Collecting Locality:
- North America, Mexico, Chihuahua
Shiny metals have been associated with beauty and wealth throughout human history. Gold, silver, and copper are three of the few metals that sometimes occur uncombined with other elements in nature, so it was relatively easy for ancient humans to collect them for personal adornment and trading. Copper jewelry emerged about 7,000 years ago, and the Egyptians began to make gold jewelry between 3,000 and 5,000 years ago. In many cultures, people put much of their wealth into their jewelry, both metallic and non-metallic (stones and bones), and used it as currency before the idea of money developed. The first coins appeared in the areas now known as Turkey and Greece about 2,600 years ago. Over the centuries, humans added so-called "base" metals to the gold and silver in coins, whose value became determined by law, not the actual value of the metals in the coin. Today, a U.S. "copper" penny is 97.5 percent zinc with a thin coating of copper; higher-denomination coins have a copper core covered with a copper-nickel alloy.