Leaders of states in the U.S. which have significant mineral deposits often create a state mineral, rock, stone or gemstone to promote interest in their natural resources, history, tourism, etc. Not every state has an official state mineral, rock, stone and/or gemstone, however.
In the chart below, a year which is listed within parentheses represents the year during which that mineral, rock, stone or gemstone was officially adopted as a state symbol or emblem.
Garnets are a group of silicate minerals that have been used since the Bronze Age as gemstones and abrasives.
A thunderegg is a nodule-like rock, similar to a filled geode, that is formed within rhyolitic volcanic ash layers. Thundereggs are rough spheres, most about the size of a baseball—though they can range from a little more than a centimeter to over a meter across. They usually contain centres of chalcedony which may have been fractured followed by deposition of agate, jasper or opal, either uniquely or in combination. Also frequently encountered are quartz and gypsum crystals, as well as various other mineral growths and inclusions. Thundereggs usually look like ordinary rocks on the outside, but slicing them in half and polishing them may reveal intricate patterns and colours. A characteristic feature of thundereggs is that the individual beds they come from can vary in appearance, though they can maintain a certain specific identity within them.
Grossular is a calcium-aluminium species of the garnet group of minerals. It has the chemical formula of Ca3Al2(SiO4)3 but the calcium may, in part, be replaced by ferrous iron and the aluminium by ferric iron. The name grossular is derived from the botanical name for the gooseberry, grossularia, in reference to the green garnet of this composition that is found in Siberia. Other shades include cinnamon brown (cinnamon stone variety), red, and yellow. Grossular is a gemstone.
Sunstone is a microcline or oligoclase feldspar, which when viewed from certain directions exhibits a spangled appearance. It has been found in Southern Norway, Sweden, various United States localities and on some beaches along the midcoast of South Australia.
Mr. Chairman, we would recommend that rather than naming the state rock "limestone", which is prevalent in different forms around the country, we should declare a limestone specific to Kansas as the state rock. Our recommendation would be Greenhorn limestone, the famous "post rock" limestone that has the largest distribution statewide,[sic - Cottonwood and other limestones have larger distributions in the state] running from Ford County all the way to Washington County [i.e., Smoky Hills], and can be seen as fenceposts everywhere in between."