AKA: Buttermilk Falls, Black Rock, Clarence, Coniferous, Diver's Lake, Moorehouse, Fort Erie Chert

Color: The color of Onondaga chert can vary from light to dark gray to a mottled bluish gray to a dark brown or black or tan.  Quartz vugs may be present. 

Luster: The luster may range from dull (course grain) to a glassy vitreous (fine grain)

Silica Fabrics / Fossils: Include chalcedony or quartz mosaic infilling and may have fossils of tabulate corals, crinoid columunals, and Rugose corals  Microfossils include Hapsidopalla, brachiopods, echinoderms, corals, bryozoan and trilobites

Patina: The patina can range from buff to yellow and is always lighter than the original material.

Heat Treatment:  Heat treatment is not usually used due to degrading of the stone, but heat treatment does produce red, purple, or white hues

Knapping:  Knapping of this material often produces a petroleum smell

Notes:  Onondaga Chert can be distinguished from Bois Blanc Formation Chert by the presences of Hapsidopalla in Onondaga Chert.  It is similar in characteristics to Fossil Hill Formation Chert, however, Fossil Hill Chert has Navifusa and Polyedryxium which is absent in Onondaga Chert. 

 

 

 

 

 

 

 

 

  

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Distribution Comments:

Onondaga chert is found in Onondaga Limestone Formation on the Niagara Peninsula.  Onondaga Chet is found from the Province of Ontario, across western, central and eastern New York to the Hudson Valley, turning south‐south‐westward to New Jersey and Pennsylvania.  Primary outcrops occur in Erie, Genesee, Monroe, Livingston, Ontario, Seneca, Cayuga, Onondaga, Madison, Oneida, Herkimer, Otsego, Schoharie, Albany, Green, Columbia, Ulster, Sullivan, and Orange counties, New York.  Other outcroppings are found throughout the Hudson River basin and the Mohawk River basin.  It is found as cobbles in river valley's and along the Lake Erie shore.