Vermont's complex geology has led to the development of a diverse and
economically healthy minerals industry which began in Vermont over 200 years
ago.  Because three of Vermont's rocks are equally important to the state's
economy, all three - granite, marble and slate - were formally recognized as
State Rocks by Act No. 221 of 1992.

Granite is an igneous rock found along the entire length of the eastern part
of the state.  It is mainly composed of feldspar, quartz and mica.  The
granite from Barre is world-famous, and the Westmore-Morse Quarry in Barre is
the world's largest monumental granite quarry.  Vermont granite is exported
to many states and countries for use as building stone and is prominent in
the Vermont State Capitol.

Marble, a metamorphic rock composed of the mineral calcite, can generally be
found in southwestern Vermont.  The marble quarry in Danby is the world's
largest underground quarry, covering twenty acres.  Vermont marble ranges in
color from pure white to black.  It has been used in building Radio City
Music Hall, the National Art Gallery, the Jefferson Memorial and the Vermont
State Capitol.

Slate is a metamorphic rock found in southwestern Vermont.  It is formed by
the compaction and heating of clay, silt or mud.  Vermont slate varies in
color from red, green, black and purple.  Because it splits into thin slabs,
slate is used for roofing shingles, sidewalks and floor tiles.

       from Office of the Secretary of State, Vermont Legislative Directory
  and State Manual, Biennial Session, 1993-1994, p. 23.