Calcite

As a calcite lover I am always on the lookout for the unusual. This specimen is comprised of highly irregular modified crystals compounding into larger crystals. Two distinct trigonal crystal outlined by later stage growth present a challenge in understanding the morphological sequence. I can only guess that the two central crystals broke off at some point in time and during the continued formation of the specimen. The terminations healed but the solution migrated along the outer terminal faces.  Fascinating to contemplate.

Locality: Rensselaer Quarry, Rensselaer, Indiana

Composition: calcium carbonate