Jewels are the end result of a process begun billions of years ago when the Earth was first formed. All that existed originally were the elements. Common elements you may be familiar with include oxygen, silicon, and carbon. Gold and silver are also elements. Far below the Earth's surface, where they were subjected to tremendous heat and pressure, certain elements combined to form minerals.
Atoms of an element may combine with other atoms of the same element; or they may combine with atoms from other elements to make compounds. Sulfur is a pure mineral, that is, it contains only sulfur atoms. Sulphur atoms may also combine with iron atoms to form a compound mineral called pyrite.
Minerals, and substances made from them, all belong to the mineral kingdom, which includes more than 3000 members. Approximately 100 minerals are classified as gemstones. Although a few gemstones are used for industrial purposes, most have value solely to collectors. Only about a dozen gemstones are suitable for use in jewelry.
Due to the exquisite way in which most gemstones crystallize, they were described as "the flowers of the kingdom" by Abbe Hauy, an early French crystallographer.
Diamond, which is pure carbon, is the only gemstone formed from one element. All the other minerals that we classify as gemstones are compounds--they are minerals that include atoms from more than one element.
Minerals formed from more than one element are also called chemicals. Like other minerals, gemstones can be described by chemical formulas. For example, quartz is a combination of silicon and oxygen called silicon dioxide.
A gemstone's chemical composition determines its appearance. Although they are both blue stones, sapphire and turquoise look and feel entirely different. That's because sapphire is an aluminum oxide (aluminum and oxygen) with a trace of titanium, while turquoise consists of aluminum, phosphate, and copper.
Another important factor affecting the appearance of gemstones is the way in which the atoms are bonded together within the stone. Diamond and graphite both are pure carbon and have identical chemical formulas. However, they are entirely different substances due to the way the carbon atoms in each fit together. Carbon atoms in a diamond crystallize in a tightly-bonded regular
| Here's the follow-up discussion on this article: | View all related messages |
For a complete listing of article comments, questions, and other discussions related to Sandra I. Smith's Gems & Minerals topic, please visit the Discussions page.