Dolomite is another common mineral in sedimentary rock. It’s a carbonate mineral CaMg(CO3)2. Crystals are usually rhombic though growth can create a saddle-shape crystal. Color is commonly pearly white, but it can be pink, yellow, orange, brown or red. Those with the reddish tinge have iron in the atomic structure and are called ferroan dolomite.
Corydon Crushed Stone Quarry in Harrison Co., Indiana, is a top 3 or 4 American locality for its pink color. Intensity is variable and the color disappears if the specimen is left outside for a period of months or years.
Harrodsburg, Monroe Co., Indiana, is a famous collecting locality for geodes. One of my favorites is the dolomite with a little iron giving it a vivid color.
Sellersburg Quarry, Clark Co., Indiana, has rare vugs of dolomite, calcite and pyrite in the Jeffersonville Limestone.
Lebanon Quarry, Marion Co., Kentucky, has pale dolomite crystals in a dolostone breccia and in rare calcareous nodules in the New Albany Shale.