Page 27 - visitorGuide

specifications. Among the books on the desk are The Nature and Origin of
Deposits of Phosphate of Lime, Penrose’s Ph.D. thesis at Harvard published
as Bulletin 46 by the U.S. Geological Survey in 1888, and bound volumes of
documents pertaining to the founding and rapid growth of GSA. The desk
drawers contain some of his correspondence, his extensive field notes made
during travels to mining locations around the world, and some of his lecture
notes. In 12 years, he visited 60 countries.

The Persian rugs, carved wooden elephants, Buddha, and cast elephant
on the desk were probably purchased by Penrose in Asia in 1901. The globe
is one of a matched pair owned by Richard Penrose and his younger brother

Spencer Penrose. Spencer’s globe is in the lobby of the
Broadmoor Hotel in Colorado Springs. The two brothers
were deeply involved in the early development of the ex-
tensive copper deposits in Bingham, Utah, and the gold
deposits at Cripple Creek, Colorado.
The Penrose Library, some books of which are
located in the Penrose Room and the balance in the
Council Room on the second floor, is a comprehen-
sive and rare collection of books documenting early
voyages and explorations.The collection reflects the
wide-ranging interests of Penrose. Although some
of the volumes have been restored, nearly all
retain their original bindings, and many con-
tain lovely lithographs and hand-colored il-
lustrations.

■ Amethyst Geode
Immediately after the Penrose Room, you will see the truly eye-catching am-
ethyst geode from Rio Grande do Sul, Brazil. Amethyst is a purple variety
of quartz commonly found in fractures and cavities in basalt. Basalt forms
from cooled lava and contains open cavities, where there were gas bubbles in
the lava. Amethyst and other minerals crystallize from mineral-bearing fluids
that enter the cavities. The crystals line or fill the cavities, forming geodes of
various sizes. This unusual specimen is one of the largest of this quality ever
found, weighing in at more than 300 kilograms (660 pounds). Approximately
two months of careful hand labor was required to extract this specimen from
the Miocene basalt that surrounded it.
Purchased by the Society.

■ Wind-Sculpted Stone of Chert and Dolomite
Directly across the atrium is a set of stairs leading down to two large speci-
men cases on the garden level. On your way down, you will notice a striped
stone mounted on the wall. With alternating layers of blue-gray dolomite and
dark gray chert, this sculpted stone is from the Johnnie Formation (southern
Death Valley, California) of late Precambrian age and is estimated to be about
600 million years old.

The chert is resistant to wind erosion and thus stands out in sharp contrast
to the softer dolomite, which is abraded more easily and rapidly. The chert,
being very hard, is also more polished than the soft dolomite.
Gift from Bennie W. Troxel, former science editor of the Society.

If you take the stairs down, you will see two wooden specimen cases.

17FIRST FLOOR EXHIBITS