The different regions of the USA all have very distinct minerals, which is related to both the geology and exposure of interesting material. Specimen bearing material can be exposed in a natural occurring outcrop or by removal of overburden from blasting, mining, and/or quarrying. Some areas, such as the New York City area and its suburbs are rich with occurrences of fine minerals but inaccessible due to development or other reasons. Contrasting this, some areas such as the state of Nebraska would be easy to collect minerals in if it were rich in occurrences. This state is one of only a few that have nearly no mineral diversity.
Below, is a brief description of the most notable minerals from the different major regions of the US.
New England
New England is known for its striking variety of different mineral species in such a small area. This is because the area has a very large diversity of igneous, sedimentary, and metamorphic environments. It is perhaps best known for occurrences of gem minerals in pegmatites. Especially for tourmaline found at Mt. Mica, Paris, Maine, and the Gillette Quarry, Haddam Neck, Connecticut and for aquamarine and heliodor found in many pegmatites in nearly every New England state but especially ME, NH, and CT.
Many amethyst localities are also present in New England, especially in Maine, Massachusetts, and Rhode Island. Also, the basalt trap rock quarries in Connecticut and Massachusetts produce some of the finest babingtonite and prehnite specimens in the world.
NY/NJ/PA and the Mid Atlantic
New York is a large state that has thousands of mineral occurrences. The most famous mineral from New York by far are Herkimer Diamonds – finely crystallized, water clear quartz crystals found in and near Herkimer County. Amazing specimens of dravite crystals from Power’s Farm, St. Lawrence County; fluorite from Walworth, Wayne County; and chrome tremolite from Gouvernour, St. Lawrence County are also examples of other very popular minerals originating in New York.
New Jersey’s many quarries in the Northeastern portion of the state exploit a very vesicular basalt that is extremely rich in crystallized mineral specimens of prehnite, stilbite, calcite, heulandite, quartz var. amethyst, natrolite, and many others. The primary zinc oxide deposit at Franklin, Sussex County. 70 minerals have been discovered in the Franklin Mining District
Pennsylvania and the rest of the Mid Atlantic states have many nice pegmatite and serpentinite minerals in the east and limestone-associated minerals like calcite and celestine. The Wheatley Mine in Phoenixville, Pennsylvania is known to produce some of the finest pyromorphite in the US and is still open to field collectors.
Southern States
The Southeastern states vary in that some states like North Carolina and Georgia produce any specimens but some like Florida and West Virginia produce little to none. North Carolina produces very fine emeralds and gem quality green spodumene called Hiddenite. Arkansas is famous for yielding the largest diamonds in the country and for its production of fine quartz crystals near Hot Springs. North Carolina and Georgia have also produced lots of gorgeous amethyst and aquamarine crystals.
Midwestern States
The Midwest is largely mineralogically poor but a few localities have produced gorgeous specimens. The Cave in Rock District in Illinois is known for some of the largest fluorite crystals in the world which often exhibit nice phantoms and are purple or yellow. The Keweeenaw peninsula of Michigan is rich with copper deposits and is known for well crystallized specimens. The famous Tri-State district of Missouri, Kansas, and Oklahoma was formerly mined for lead and zinc and is still famous for its amazing specimens of calcite chalcopyrite, sphalerite, and galena.
Southwestern States
The Southwest is the most famous region of the US for minerals and is home to the Tucson Gem and Mineral Show, which is the largest event of its type in the world. Excellent specimens of orange wulfenite come from the Red Cloud Mine in Arizona. Some of the world’s finest azurite and malachite ever found have been dug from Bisbee, Arizona. Gorgeous crystals of red beryl and topaz come from rhyolite mountains in Utah. Amazonite and the world’s finest rhodochrosite have both been famously dug from Colorado.
West Coast, Alaska, and Hawaii
California is extremely diverse in geological environments and has produced some of the finest minerals out of any state. The pegmatites near San Diego are famous for vibrant, amazing tourmalines, kunzite, morganite, spessartine, and others. California is also home of the extremely rare and unusual mineral Benitoite, which is sometimes faceted into gems. Benitoite is only found in a few other locations worldwide and none of them yield crystals as large or high quality as what is found in California. California is also famous for its gold rush, and since then has provided collectors with many fine gold specimens.
Alaska is very mineral rich but most of the material mined from the state is crushed and smelted. Some of the world’s finest epidote has been found on Prince of Wales Island. Many other minerals have been found in Alaska in notable quality such as barrerite, fluorite, almandine, rhodonite, cinnabar, stibnite, rutilated quartz, amethyst, cassiterite, gold, silver, and platinum.
Hawaii was formed very recently, geologically speaking. It has very few occurrences that yield fine minerals. There are a few localities for quartz crystals, zeolites, and olivine, but they are not nearly as good as what’s found on the mainland.