f019253d_The_Delaware_Geological_Survey_inerals_of_the_Red_Clay_Valley_Description
[Rock Type] Quartz [Description] 
A glassy, transparent to translucent mineral that breaks and fractures like glass. Its color is usually white to gray. Quartz is present in almost all Piedmont rocks.
Common Rocks and Minerals of the Delaware Piedmont | The Delaware Geological Survey
Description