Sunday, December 19, 2010

Fibrous or Needlelike Mineral Growth in Orthospirifer

While sorting Devonian brachiopod specimens for upcoming posts on beekite and internal coral growths I came across this oddity.  It appears to be a needlelike or fibrous mineral that grew inside the fossil. 

Looking at the list of Indiana minerals that are needlelike are: aragonite (calcium carbonate), strontianite (strontium carbonate --RARE), and geotite (iron oxide in water).  Indiana minerals that are fibrous are gypsum (calcium sulphate in water).  So I think it is either gypsum or aragonite.  Any suggestions as to what mineral this might be?

The material does not respond to long or short wave UV.

This Orthospirifer brachiopod was found in the Jeffersonville Limestone of Clark County, Indiana.

Additional photographs show specimen plus it magnified 20x with a loupe, 40x & 100x with a microscope.