Walked the upper east side with Sidney Horenstein today, the rock guy from the Museum of Natural History. 

 

A period news account says that the old Otto Kahn mansion (now the Convent of the Sacred Heart) at 91st and Fifth was made of "limestone imported from France."   And indeed it looks to me like what I have always thought of as "French limestone" - that softer-looking stuff, with lots of occlusions and "bad" weathering, with lots of holes where the snails fell out.

 

Upon inspection, Sidney said that he noticed that there were many Trigonian fossils, and that he suspected it was actually Texas limestone - Trigoniidae are only found, in fossil form,  in Texas.

 

How many of you would feel confident about identifying "French" vs. "Texas" limestone?  Christopher