- GeoRef, Copyright 2008, American Geological Institute. Reference includes data from Bibliography and Index of North American Geology, U. S. Geological Survey, Reston, VA, United States
Hydrated and dehydrated halloysite, allophane, crandallite, gibbsite, kaolinite, iron oxides, manganese wad, and barite are associated with quartz conglomerate of the early Pennsylvanian Mansfield formation in southwestern Lawrence County, Indiana. Halloysite is found as lenses in the conglomerate and as rounded particles as large as pebble size. Allophane is found in lenses and exhibits columnar and botryoidal structures. Crandallite has formed at the expense of allophane. Manganese wad is found both as coatings on quartz pebbles and as pebble-free lenses as much as 6 in. thick. Most lenses of wad contain gibbsite and hydrated halloysite. Kaolinite occurs as rounded pebbles and as irregular particles between quartz pebbles. Iron oxides appear as irregular bands and stainings throughout the conglomerate. Two layers of well crystallized barite, each half an inch thick, are found about 200 yards SW. of the quarries at the contact of a Mississippian limestone and overlying red clay and quartz pebble residuum.