|
Smokey
Quartz and Fledspar Crystals at Rock Corral Canyon in the Mineral
Mountains, Beaver County
(Source
Dustin L Rooks)
Back To Beaver City
Smoky
quartz and microcline crystals from the Rock Corral area collected
by the author in November of 1996. Quarter in foreground for scale.
Geologic
information: The Mineral Mountains,
located in Beaver County, make up the largest exposed plutonic body
in Utah. Rock compositions range from quartz monzonite in the
northern half of the pluton to granite around Rock Corral Canyon in
the south.
Excellent
crystals of smoky quartz and feldspar are found in vugs or cavities
in the granite. They formed when cooling fractures in the granite
were filled by late-stage pegmatites consisting of quartz,
microcline, and plagioclase. Quartz occurs as clear to smoky,
euhedral crystals up to three inches long while microcline is
commonly found as euhedral, equidimensional crystals averaging
approximately 0.75 inches in width. Occasionally, large pseudomorphs
of limonite after pyrite can be found in these areas as well.
How to
get there: Travel 0.7 miles south of the
railroad tracks on State Route 21 from Milford where a Corral
Recreation Area sign will instruct you to turn left (east) from the
highway. This road is paved for a short distance but then turns to
sand. Continue from the turn-off 5.4 miles to an intersection. Take
the left fork and continue for 1.2 miles to another intersection.
Keep right at this intersection for 2.7 miles to the first outcrop
or inselberg on the left. You can park here or continue to the
picnic area in Rock Corral Canyon.
Where to
collect: Although the quartz and feldspar
are not confined to Rock Corral, the best-developed crystal
specimens seem to occur within a half-mile radius of the picnic
area. As mentioned above, the crystals are found in vugs. Look for
areas where the quartz and feldspar are easily visible as coarse
veins. Examine these areas closely as occasionally they open up into
cavities where the crystals had space to grow.
Useful
maps: Beaver and Wah Wah Mountains South
1:100,000-scale maps, and a Utah highway map. These are best for
navigational purposes. Also, the Adamsville and Bearskin Mountain
1:24,000-scale maps. Topographic maps can be obtained from the
Natural Resources Map & Bookstore, 1.888.UTAHMAP; 801.537.3320,
fax - 801.537.3395.
Land
ownership: Bureau of Land Management (BLM)
public lands.
BLM
collecting rules: The casual collector may
take small amounts of petrified wood, fossils, gemstones, and rocks
from unrestricted federal lands in Utah without obtaining a special
permit if collection is for personal, noncommercial purposes.
Collection in large quantities or for commercial purposes requires a
permit, lease, or license from the BLM.
Miscellaneous: A hat and water are
essential.
Tools
recommended: Safety glasses, hammer,
chisel, and patience are a must. Have fun collecting!
About the
author: Dustin L. Rooks is a Junior at
Southern Utah University where he is majoring in both geology and
botany. He is a native of Vernal, Utah where he spends summers
conducting range studies for the National Forest Service and
collecting rocks, minerals, and fossils.
|
