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A pseudomorph is a mineral that replaces another mineral,
molecule by molecule, without changing the original crystal form.
In this sense, the process that forms petrified wood (replacement
of the wood by silica) is somewhat similar to the process in
minerals.
The Pelican Point Goethite pseudomorph locality is the
premier world location for Gothite psedomorphs after pyrite. This
locality has been producing world class goethite specimens since
the 1930s. It was a very popular collecting locality in the late
40s and early 50s after which people, having collected the easily
accessible material, came to the conclusion that the locality was
basically “played” out. The area received relatively
little attention until it was re-explored by our company in the
spring of 1978. At this time we found a new layer of crystals,
deeper than the “exhausted” upper layer. We worked this
layer for the better part of three weeks, on a part time basis,
producing some really great clusters of goethite pseudos. The
project was, however, abandoned because of problems involving the
cleaning and preparation of the specimens. Since the specimens
were dug in place rather than weathered out on the surface, they
were still encased in clay and various Fe alteration products
that were nearly impossible to clean off. Cleaning even small
specimens took 10 to 15 hours or more of tedious hand labor using
dental tools and wire wheels. In the summer of 1995 we made
another attempt at mining this great locality, however, this time
new techniques were available for handling the previous
preparation problems that we encountered. We now use an air
abrasive machine (micro sandblaster), using a very fine mixture
of glass beads and crushed glass, to remove all of the clay and
alteration products. This process does not adversely affect the
goethite, however, in certain specimens, the process sometimes
dulls the surface luster. For these pieces we use a polishing
compound to restore the original luster without altering the
specimen in any way.
As mining continued, new layers were uncovered. The deeper
layers show far less alteration (pseudomorphing) than those
closer to the surface; in fact, the deepest zone produced
specimens that were 99.9 % + pyrite. During the summer of 1995 we
collected some of the finest examples of these unique
pseudomorphs ever to have come from this area.
Since the pseudomorphs form as a result of oxidation (due to
ground water), it is not at all unlikely that at greater depth,
we should encounter totally unaltered pyrite specimens. We plan
to pursue this possibility as early as the summer of 1996. If
indeed unaltered pyrite is found they would be some of the most
spectacular specimens of pyrite to come out in many years.
Location: Pelican
Point is located in the lake mountains, on the western side of
Utah lake, in Utah Co. It lies about 45 miles SW of Salt Lake
City or 15 miles ESE of Lehi Utah.
Age and Composition:
The lake mountains are composed primarily of rocks of Paleozoic
age. The formation that produces the goethite is Mississippian in
age and is made up of various layers of limestone, dolomite, and
calcareous mudstone (the specimens occur in the calcareous
mudstone). The formation represents a shallow, stagnant, lagoon
environment. The layers with the goethite contain an abundance of
marine fossils i.e. brachiopods, bryozoan etc.
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