FAQ14

Date: 08-Oct-98

Where are good mineral-collecting sites in Indiana?

IMPORTANT: You should seek permission from the Indiana Department of Transportation and from the Indiana State Police or local county sheriff's office to collect along road cuts. If you do collect along road cuts, be sure that you and your vehicle are well off the road and do not pose a traffic hazard. Collecting on private property requires permission from the owner. Collecting at state parks is strictly prohibited, but limited collecting may be possible at some state or federally owned or managed properties if you have obtained permission or a permit. For information about collecting in the Hoosier National Forest, go to the forest's Web site, send an e-mail message, or call 812-275-5987. For information about collecting at state forests or reservoirs, contact the Indiana Department of Natural Resources.

The best rock, mineral, and fossil collecting localities in Indiana are active and abandoned stone quarries. Unfortunately, most of the quarries where the best specimens could be found are now closed to the public. Abuses of courtesies extended by quarry owners to collectors have resulted in almost total prohibition of public access to those quarries. Further aggravating the situation are several federal mining regulations that severely limit public access to most stone quarries. It may be possible to gain such access, however, by contacting quarry owners, especially those of smaller operations. Hard hats are usually required and you are expected to provide your own. The IGS publication Directory of Industrial Mineral Producers in Indiana is a useful source of the names, addresses, and phone numbers of the owners and operators of Indiana's currently active stone quarries.

Much of the southern one-third of Indiana, particularly that portion not covered by glacial drift, is blessed with an abundance of bedrock outcrops. The major highways that traverse this part of the state cut through thick bedrock exposures at numerous places along their trend. Indiana 37 south of Martinsville, Interstate 64, Interstate 65 south of Columbus, Indiana 135, and U.S. 231, to name a few, expose thick sections of Paleozoic rocks. Along these road cuts, and within the stream valleys that exist near them, the collector may often find worthy specimens of minerals, including sphalerite, quartz, calcite, and pyrite.

The best mineral specimens are often found within geodes. Most geodes formed long ago when the rocks that now contain them were still soft sediment. Many Indiana varieties began as cauliflower-like growths of a salt called gypsum that were gradually encrusted with an overgrowth of silica. The gypsum that remained in the center of the growing geode dissolved, leaving a cavity that was later filled with a mineral--typically quartz or calcite. Other more exotic minerals found in Indiana geodes include millerite, celestite, strontianite, barite, and amethyst. Still other geodes formed by the chemical replacement of calcite nodules by silica or by the oversilicification of hollow fossils. By whatever means the geodes came into existence, they have long attracted the interest of collectors. Geodes are found mostly in creek beds where they accumulate as erosional lag deposits left behind by the weathering of bedrock and soil material.

John Hill