From the "we never knew this, how very interesting" department: U.S. Silica, one of the country's largest sand and proppant companies providing frack sand to drillers around the country, is headquartered in...anti-drilling Maryland? Yep--HQ for U.S. Silica is Frederick, MD--not all that far from both Washington, D.C. and Baltimore. Maryland, like New York, is currently