(Some places will even cut, polish and set found minerals into jewelry for a fee.) In North Carolina, for example, 50,000 treasure hunters try their luck at Emerald Hollow Mine each year. Today nearly every state has at least one fee-based mine or dig site that’s open to the public with a 'finders, keepers' policy that allows visitors to pocket their finds. Gold is neither a gem nor a mineral-it’s a chemical element.) Gems are precious or semiprecious minerals that can be cut and polished into colorful stones. ( Generally speaking, minerals are inorganic objects containing a specific chemical makeup and molecular structure. history that even today every state in the union has either a state gem or mineral-or both. The hunt for buried treasure is so interwoven into U.S. One of the earliest accounts of mining in what is now the United States comes from the Pueblo, a Southwestern tribe that began mining for turquoise some 2,600 years ago. As early Anglo settlers spread the word about the wealth of buried treasures beneath the land, immigrants flocked to the colonies to stake their claim. Often called “rockhounding,” the search for gems and minerals has been popular for decades. The secret is knowing where to sink your shovel. Across the United States there are dozens of public mining and digging sites packed with everything from diamonds and emeralds to jade and sunstone. They're also identified by the ways in which they break, or the type of mark, or streak, that they leave when rubbed on a laboratory tool called a streak plate.Do you dream of the good life? For a lucky few, treasure may lie hidden beneath your feet. Minerals and gems are classified by their physical properties, including hardness, luster, color, density, and magnetism. Different trace elements can produce other colors, allowing beryl to form semiprecious stones such as aquamarine. The color comes from additional traces of chromium and vanadium.

Emeralds are formed of a mineral called beryl whose chemical formula is a complex mix of beryllium, aluminum, silicon, and oxygen.

Corundum also forms sapphire in many colors, which generally come from trace mixtures of iron, titanium, and chromium. The red color is caused by traces of chromium.

Rubies are formed of a mineral called corundum, comprised of aluminum oxide.

Graphite is also made of carbon atoms, but with a different arrangement-explaining why diamond is the hardest mineral and graphite (used in pencil lead) is one of the softest. Formed under extremely high pressure hundreds of miles underground, they are found in very few locations around the world.

Diamonds, made of carbon atoms, are the hardest natural substance found on Earth.

Precious gems are formed in different ways and composed of different materials, meaning their appearances vary vastly.

There are a number of semiprecious gems, many quite beautiful, but diamonds, rubies, sapphires, and emeralds continue to qualify as 'precious.' (At one time, amethyst was also considered a precious gem, but large reserves were later found in Brazil, reducing its value.)

Historically, gems have been divided into precious and semiprecious classes. It's only when they are cut and polished that they obtain the brilliance and luster that gives them their value. Uncut gems often look fairly ordinary–like rocks. Many minerals form beautiful crystals, but the most prized of all are gemstones. Oxides, sulfides, sulfates, carbonates, and halides are other major mineral classes. Silicates-including quartz, mica, olivine, and precious minerals such as emeralds-are the most common class of minerals, as well as the major components of most rocks. Rocks themselves are made of clusters or mixtures of minerals, and minerals and rocks affect landform development and form natural resources such as gold, tin, iron, marble, and granite.

Geologists can tell a chalcedony from the arrangement and structure of its crystals. Chalcedonies include many types of cryptocrystalline quartz gems and feature a number of different colors.

Gems and minerals