It is described as a massive biotite-quartz monzonite[2] which intrudes through the Baltimore Gneiss at a single locality surrounding the town of Granite, Maryland.

This mass of granite, which is evidently intruded into the gneisses, is entirely enveloped by them and sends no dikes or apophyses into the surrounding rock.

These are chiefly of gneiss, and they occur often in huge irregular blocks six to eight or even ten feet in size, showing narrow rims due to contact metamorphism.

The color of the rock is bright gray, with something of a luster imparted by the quartz and the unaltered feldspars, the latter often giving an additional faint pink tone.

The mica occurs in evenly disseminated fine black flakes which emphasize the grain of the rock and only slightly subdue the bright fresh aspect of the stone.

"[6] The 1898 account of Edward B. Mathews of the Maryland Geological Survey[5] of the quarries at Granite (formerly known as Waltersville) begins with boulders attracting the attention of "several enterprising men from New Hampshire," (Sweatt, Putney, and Riddle) who commenced quarrying operations about 1832-33, and supplied stone to the Baltimore and Ohio Railroad.

This rock developed into a fine ledge, surpassing all the granite around in quantity, quality and easy access, so that all the boulders in which Sweatt, Putney and Riddle were interested were at once abandoned.

Woodstock granite can be found in the United States Capitol, Thomas Viaduct, "the Library of Congress, the inner walls of the Washington Monument, the Old Patent Office, and the Baltimore Custom House."