Dolostone is a chemical sedimentary rock composed of dolomite (CaMg(CO3)2 - calcium magnesium carbonate).  It is usually gray-colored, finely-crystalline, and often has irregularly-sized & irregularly-shaped holes called vugs.  The dolostone shown below has a sucrosic (sugary) texture with abundant, relatively small vugs, plus beautiful, brassy-colored pyrite crystals that line part of a large vug (reportedly a ~2 foot-diameter subspherical cavity).  Pyrite is iron sulfide (FeS2) and many of these crystals have colorful-iridescent oxidation films.


Stratigraphy & age: Lockport Dolostone (“Lockport Dolomite”), upper Niagaran Series (upper Wenlockian), upper Middle Silurian


Locality: sidewall of open-pit quarry, ~300’ below the surface, National Lime & Stone Company’s Buckland Quarry, just southwest of the town of Buckland, northern Moulton Township, northern Auglaize County, northwestern Ohio, USA.


Pyrite crystals on sucrosic dolostone (above & below) from the Lockport Dolostone at Buckland Quarry, northwestern Ohio, USA.




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