Economic Geology

Contrary to the widely held belief, the Hoosier State has many resources to offer other than its yearly corn and bean crop. There are many types of geological resources in Indiana, some obvious, and some less apparent. For example, most people know that Indiana limestone is quarried extensively, but the fact that oil is produced in Indiana escapes the majority's awareness. Below, we will explore a few of the apparent, and some less apparent geologic resources Indiana has to offer.

© Michigan State University Department of Geography


Limestone, Sandstone & Gravel

Above is a picture of the largest limestone quarry in the world, located close to the shore of Lake Huron in Northern Michigan. While you won't see any quarries in Indiana of comparable size, it might be made up for in volume. There are now more abandoned quarries and gravel pits than active, but at one time not so long ago, the stone economy was booming, and so was production (see map below). Indiana limestone has been used for many applications, including building stone (notably, used in the Empire State Building), fertilizer lime, and gravel to name a few.

In addition to Limestone, there has been fairly extensive quarrying of Hoosier sandstone. This is used primarily as an abrasive, but has also been used as building stone to a small extent.

Sand and gravel pits have, in the past and in the present, provided a significant source of income to the state. Due to the large amounts of glacial till and outwash, and somewhat due to the lake morraines and dunes of Northern Indiana, it was remarkably easy to start a new operation gathering and shipping these valuable sediments across the Midwest (see map below).


Left: Map of Abandoned Limestone Quarries and Rock Strata ©Nathan Scott, 2004

Right: Sand & Gravel Exploitation and Availability Map ©Nathan Scott, 2004

Below: Crushed Stone Quarry © Michigan Tech Geology Department


Coal mining in Indiana has all but ceased in recent years, but, as in the case of some gravel pits, was once commonplace. According to David F. Hess, in 1964, coal was Indiana's "most important mineral commodity" bringing in $57,246,164. Much of the coal mined in this state was/is used by electric companies in the vicinity. Nearly all Indiana coal comes from strip or pit mines dug into Pennsylvanian strata in the Southwestern part of the state (see maps below).


Above Right: Indiana Coal Mine Distribution Map. © Nathan Scott, 2004

Above Left: Coal Distribution Map ©


Below Left: 2001 Oil Well Drilling Data © 2002, IGS Mineral Economic Series 48

Below Center: Chart of Indiana Strata Drilled for Oil. © 2002, IGS Mineral Economic Series 48

Below Right: Indiana Petroleum Fields Map. © 2004, Nathan Scott.


Petroleum Resources

Though never a major producer, Indiana has exported its share of crude in the past, and continues to pump dollars out of the ground in the form of petroleum. Indiana oil was first pumped from Ordovician rocks in East-Central Indiana and from Devonian age rocks in Southwestern Indiana drilled in 1889. Soon, the drillers and geologists started to find that there was more oil to be had from certain areas of Upper and Mid-Mississippian age rocks. For a time in the sixties, petroleum and natural gas were bringing upwards of $80,000,000 per year to the state, with production of oil into the tens of millions of barrels and natural gas into the hundreds of millions of cubic feet per year. However, this was not to last.

In 2001 production of natural gas was only 1,063,673 cubic feet and oil was down to 2,022,803 barrels. Though exploratory drilling and re-drilling of old wells continues, oil is becoming hard to find in the Hoosier state, as shown by the graphs below.

© 2002, IGS Mineral Economic Series 48


Above: The largest nugget of gold ever found in Alaska, weighing in at 294.10 Troy Ounces! It is currently on sale for $500,000 US Dollars. © Alaska Mining and Diving Supply

Diamonds and Gold?!

Yes, there are actually Diamonds to be found in Indiana, along with small amounts of gold. Though certainly not in economic proportions, diamonds as large as 4 carats (Brown County) have been found. The Indiana Geological Survey only has 38 recorded diamond finds over the history of Indiana, but many may not have been reported or recorded. Most, geologists agree that the gems in Indiana are not native, but came within glacial sediments from some locale to the North. Interestingly enough, while most of the diamonds found in Indiana and the surrounding area suggest (by virtue of their size and clarity)a large source field, none has ever been found. This is not the only theory for the origin of the diamonds, as some believe there might be a local source. This theory is supported by the relatively recent discovery of a kimberlite (diamond-bearing ore) pipe in Wisconsin.

Gold, in contrast to diamonds, has been found in relative abundance in the Hoosier state. Though only a tourist attraction in Brown County, where the most gold has been panned, it has been proposed by some that, using the right techniques, Gold could be recovered in paying amounts. Historically, Brown and Morgan Counties have been the hotspot for gold searchers, but, as you can see by the map below, it (along with diamonds) has been found all across the state.Contrary to the situation with diamonds, it is thought that the gold in the area is almost certainly from gold-bearing areas in Canada and Northern Michigan.

Note to anyone planning to go prospecting for gold or diamonds in Indiana, please make sure you get the landowner's permission BEFORE setting foot on their property...lest you get shot.


Above Left: Natural cubic Diamond such as one might find in an Indiana creek. © Gem & Mineral Miners, Inc.

Above Middle: Map of Gold and Diamond finds in Indiana. © IGS Circular #12.

Above Right: Natural Diamond embedded in Kimberlite ore. © Gem & Mineral Miners, Inc.


This website was prepared as an assignment for Geosciences 211 (Physical Geology) taught in the spring of 2004 at Earlham College, Richmond, Indiana.

Copyright 2004 Earlham College. Revised May 4, 2007 . Send corrections or comments to