Many minerals can be found in Indiana and the most common amongst these are calcite and pyrite. Diamonds have also been found but these finds are very few and far between. The state is also rich with a variety of fossils and geodes.

Diamonds

Though diamond mining is not an economically viable industry in Indiana, yet a few large diamonds have occasionally been found. However the discovery of diamonds is more by chance than by actual prospecting. To date, only 38 diamonds have been recorded to be found in the history of Indiana. It is certainly possible that many more which were found that went unreported though. Still, they are exceedingly rare occurrences.

The largest diamond recorded was 4 carats in size which was found in Brown County. Morgan County is another location in Indiana from where diamonds have reportedly been recovered.

The best place to find diamonds in the U.S. is the Crater of Diamonds in Arkansas.

Calcite

Calcite is found quite extensively in the state of Indiana. It is generally found in colorless form and in yellow and brown shades. Calcite is the principal constituent of limestone and constitutes 50 percent or more in the stone.

Calcite has been mined from the Paul Frank Quarry, the Berry Materials, near Anderson City in Madison County and the Crushed Stone Quarry in Harrison County.

Calcite has also been found at locations in Bartholomew County and from locations close to Columbus.

Pyrite

Small quantities of pyrite can be found in various parts of Indiana within different rock formations present in the state. The coal fields situated in the southwestern region of the state are one location where pyrite can be found in abundance.

Pyrite can also be found at the oil shales present in the state and in central-west region of Indiana at the Rensselaer Quarry in Jasper County. Another location where the mineral can be found is near the city of New Albany in Floyd County.

Fossils

The southeastern part of Indiana has Mississippian and Ordovician formations which have abundant fossils of marine animals such as bryozoans and crinoids. Fossils from the Devonian period are found at the Falls of the Ohio State Park located at Clarksville.

Fossils of brachiopods, cephalopods, corals, bryozoans, crinoids, gastropods, conodonts, teeth, trilobites and sponges that belonged to the Upper Ordovician period can be found at the limestone formations in Jefferson County.

In Crawford County there are limestone, sandstone and shale deposits where a large number of fossils from the Upper Mississippian period can be found. These include fossils of brachiopods, horn corals, blastoids, crinoids, conularids, bryozoans, gastropods, trilobites, shark teeth and pelecypods.

Geodes

Geodes are found in various counties of Indiana. These geodes contain various minerals such as quartz, barite, dolomite, calcite, pyrite, marcasite, sphalerite and millerite. The different locations where geodes can be found are at an exposed limestone deposit close to the town of Bedford in Lawrence County, and various locations throughout Brown, Monroe, Mitchell and Lawrence counties. Old abandoned mines and quarries are often the most productive locations to search.