Many United States (US) states choose official symbols to represent the state to locals and visitors. These official symbols help to project the desired image and pride, and may help to promote tourism and travel. State symbols also serve as a way to celebrate history, or pay tribute to the state's natural resources and economic exports. While it's fairly standard for states to choose an official bird, flower, or tree, many have also selected a state stone. These state stones come in several geological forms, including rocks, gemstones, and minerals.
Not every state has an official state stone, though most have chosen at least some form of geological symbol. As of July 2011, just 21 states have an official state mineral, while 27 have a state stone or rock. Thirty-five of the 50 US states are represented by a gemstone, and many also have official soils or rivers to complement these other geological symbols.
Officials or citizens often select a state stone based on materials found in large quantities within that particular region. Others choose a material for the impact it's had on the state, either throughout history on in the present day. A state stone could represent an important natural resource, a source of pride, or a major economic draw. These types of symbols help to define the state to outsiders, and play a major role in the state's image development.
Many states have multiple state stones or rocks, while others have none. For example, Tennessee has two official rocks and Vermont has three. Limestone, sandstone and agate are some of the most common state stones, though many have also declared types of marble and granite as the official rock of the state. In Mississippi, the official stone is petrified wood, while agatized coral serves as the rock on record in Florida. Connecticut gets its nickname "The Brownstone State" from its official stone, the brownstone.
Both Missouri and Wisconsin have named galena as the official state mineral, while in Kentucky, this honor was awarded to coal. Nevada and Texas celebrate silver as the official mineral of both states. Alaska, California, and North Carolina all list gold as the state mineral, which reflects the major gold rushes that occurred in these areas.
State gems range from the diamond in Arkansas to black coral in Hawaii. Numerous states have selected agate, turquoise, or garnet as the official gem, while both Kentucky and Tennessee chose the freshwater pearl. Montana and Nevada each have two official state gems, and Texas even has an official gem cut known as the "Lone Star Cut."
