Friday, August 11, 2006

Topaz Mountain

Topaz Mountain is the southern most mountain in the Thomas Range which extends
from Tooele County to Juab County, in the central west desert of Utah.
Topaz Mountain is in Juab County.

It is the product of five distinct rhyolite flows cause by the extension of the
Basin and Range province. After the eruptions had occurred, hot gases
bubbled up through the fissures and cracks looking for a place to escape.
Some of the gases formed bubbles within the rhyolite. These bubbles are called lithophyses.

As the gases cooled, Topaz and other minerals would deposit on the sides of
the fissures and within the lithophyses.

There are a number of different minerals found in the Thomas Range,
including:

Topaz. Topaz is found in epithermal veins (epithermal means it was
deposited by hot ground water or steam). It forms as sherry-colored to
clear and pink. Crystals are 0.25" long to 3" commonly, though some have
been found up to 4" and one exceptional crystal was almost 5" long.

The color is caused by natural radiation. So when topaz is exposed to the sun
light, it fades out. The color can be replaced by re-exposing the crystals
to radiation such as x-rays.

Since the Topaz in the Thomas Range is located in a rhyolite, it often has
rhyolitic sand included within the crystal. There is NO way of cleaning
this off. Topaz crystals completely included with sand are called "sand
crystals."

Floaters are also common. This means that there is no visible point of
attachment and the crystal is terminated on all sides.

Topaz has a hardness of 8, specific gravity of 3.5, and has a strong basil
cleavage. Topaz is often confused with quartz. The quartz found in the
Thomas Range is very small (1/8") and topaz is orthorhombic where quartz is
hexagonal.

Red Beryl. Red beryl is a member of the beryl family, which also includes
aquamarine, heliodore, emeralds, morganite, and goshenite. It is by far the
rarest of all the beryl's. It is found in several places with in the Thomas
Range, including the Cove. It forms as red to red-orange to orange-violet
and pink hexagonal plates about 0.25" across and 1/16" thick. Larger ones
are rare.

Red Beryl was discovered by Maynard Bixby in the mid-1890's and hence is
often referred to as Bixbite. There is only one other documented locality for Red Beryl, and that is in the Wah Wah Mountains, also in Utah. The Wah Wah Mountains is the location that the gem material is found.

We have a great selection of Red Beryl for sale in the store.

Bixbyite. Was first discovered at what is known as the Maynard Claim. It
was discovered by Maynard Bixby at the same time he discovered the Red Beryl
also at the same location.

Bixbyite forms as black, lustrous cubes. Most are less than 0.25", though
in the past few years some exceeding 1" have been found on the north end of
the Thomas Range. Often the cubes have been naturally modified to have each corner faceted.

We have some great samples of Bixbyite for sale in the store.

Pseudobrookite. Pseudobrookite forms as slender black needles. Most are
under 0.25", though they have been found to 2". It is very difficult to
remove specimens of pseudobrookite off the rock, because when you hit the
surrounding rock, the needles pop off. Use a super glue and pour it all
over the pseudobrookite and the matrix while you are extracting the specimen
and when you get it home, soak it in acetone to remove the glue. No damage
will come to the crystals and you might end up with a keeper. Good sprays
of pseudobrookite from this location are among the finest in the world.

Weeksite. The Autunite #8 claim is the type-locality (meaning this is where the mineral was first discovered) for Weeksite. This location is marked on the topo maps of the area. It forms as yellow needles on chalcedony. Is weakly radioactive.

Durangite. Duranite is a rare mineral, and the best crystals in the world are
found in the Thomas Range.

Holfertite is a new mineral with its type locality in the Cove. It is
named after John Holfert who discovered it. Holfertite forms as very small,
bright yellow needles with the topaz and hematite. It is a uranium
silicate.

Other minerals that may be found in the Thomas Range are
Hematite, Garnets, Chalcedony, Cassiterite, Ilmenite, Fluorite, Magnetite,
Sanadine, Mimetite, Hyalite Opal, Crystobalite, Calcite, Fluorite, Rutile,
Amethyst, Zircon, and Trydimite

The Topaz Mountain area is still open to the amateur collector and here are
some pointers on finding the goodies:

This detailed information is for the Cove. There are many claims in the
Thomas Range. The Cove/Topaz Mountain is open to the amateur collecting.
That means nothing but hand tools. For more detailed information on rock hounding rules in Utah, see www.rocks4u.com/Utahrockhoundingrules.htm .

I am asked often if there is any more topaz to be found at Topaz Mountain.
YES. It just takes some skill in finding it.

The first thing you must know is that it takes patience, lots and lots of
patience. Topaz Mountain doesn't like to give up her treasures, so you must
have patience, and did I mention you must be patient?

Most of the topaz is found in the fissures and lithophysa pockets. Use a
long screw driver to probe cracks and the vugs. If the screw driver can be
moved around, then start working the fissure to open the pocket. Not all
will have topaz. And the ones that do may only have small and undesirable
topaz. Remember--be patient. Sometimes the sand and dirt will cover the
topaz in a vug, so make sure you blow or sweep the fissure out. Please be an ethical collector, and refrain from damaging specimens that you can't carefully remove. The next person may have the skills and tools to preserve the specimen.

Topaz from other locations around the world include the Zapot Claim in
Humbolt Co. Nevada where large crystals of blue topaz were discovered a few
years ago, Montana, Idaho, Colorado, California, Nevada, North Carolina,
and North and South Dakota. Brazil has produced topaz crystals to 1500 kg. Russia, and several African countries have also produced great specimens. Pakistan and Afghanistan have produced world class specimens also. Namibia produced the only true red topaz, the rarest of all. Idaho has produced great green topaz crystals which are exceptionally rare and even more rarely fluoresce under shortwave light this is rare in and of itself.

Rick

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