Nearly all the known varieties of gems and precious stones are found in the United States, and several varieties are found in Arizona. Little systematic mining has been carried on for them, and no extensive search for them has been made, except in the states of Maine and North Carolina. In most cases, the discovery of gems in the United States has been accidental in connection with other substances that are being mined, or in small veins. These gems are mostly sold in local markets; gem collectors and mineralogists also purchase them, for private collections, as a rule. Arizona Gems. The best known gems found in Arizona are turquoise, garnet, peridot, chrysocolla, azyr-malachite, malachite, agate, chalcedony, amethystine quartz, diamond (meteoric) dioptose and topaz.