everyone has heard of it, but
the rock is called “Paisanite.” It
was named after the Paisano
Pass between Alpine and Marfa
(toward Van Horn off Hwy. 90
W), and may be the only rock
unique to our area.
Believed to be found only in
Paisano Pass/Paisano Peak area
of Brewster County, Texas,
Brueske says, “The name was
given to it by a German geolo-
gist, A. Osann, a member of
the Geological Survey of Texas.
The story goes that he discov-
ered it when he got off the rail-
road train to do a little explor-
ing.”
“Paisanite is a light grey
igneous rock called rhyolite,
produced by the emissions of
one or more eruptions of the
Paisano Caldera that occurred
over a period of several million
years,” wrote Brueske. It was
described in the 1954 edition
of Webster’s International
Dictionary.
The molten lava, or magma,
cooled slowly enough that
some crystals had time to
Rock shadow box
develop.
The rock may not be terri-
bly exciting, but it is very col-
lectable and distinctive in that
the rhyolite is overlaid with
speckled
yellowish
grey
“Morrow Tuff,” which is
cemented volcanic ash.
Amateur rockhounds are
Paisanite closeup
cautioned to be familiar with
and observe the local rules and
state laws of finding fossils,
rocks and minerals in the field:
1) First and foremost, do not
trespass! This means you
should not climb fences; 2)
DO NOT collect on National
Park land; 3) DO survey the
area first, looking for potential
hazards, snakes, or poisonous
shrubs.
The Rockhound’s Handbook
by James R. Mitchell is an
excellent source for equipment
and how-to information about
collecting and identifying spec-
imens. In the magazine
Swappers’ Paradise published in
April 1959,
N. Margret
Sevetson
wrote
in
Rockhounding Hobby Made
Profitable that “To anyone fas-
cinated by rocks, and looking
for markets for ‘roughs,’ one
the best words of advice would
be to get well-grounded in
identification and comparative
values.”
That this was written in
1959 and still holds true is fur-
ther evidence that collecting,
finding, and swapping rocks
(or fossils) never goes out of
style.
Marathon:
Novaculite.
Excellent examples can be seen
on a roadcut toward the Big
Bend Park off U.S. 385.
Travel south about three miles
toward the park with Elephant
Mountain and the Marathon
Cemetery on the west (right
side of the road), past mile
marker 69, around the sharp
corner, then pull off the road
leaving plenty of safe distance
between the shoulder and
oncoming cars.
There you will see a strange
and wonderful sight, almost as
good as the Marfa Lights!
Novaculite looks pink and
shiny to me, stacked sideways,
can be seen under a micro-
scope).
Darwin Spearing
writes in the book Roadside
Geology of Texas that “Silica
needles are the only skeletal
strengtheners in the body of
sponges,” and that the U.S.
385 “road segment illustrates
the folded and faulted charac-
ter of the Paleozoic rocks of the
Marathon uplift and gives you
a chance to view close-up the
strange Caballos novaculite in
roadcuts along the way.”
Poetry to the rock collector.
If upon returning to
Marathon, you find yourself
walking along the railroad
track, you may happen upon
some grey, rounded stones,
which look out of place–like
they should be found in a river
bottom in Colorado, the edges
rounded after eons of being
rolled by a rushing river.
However, these are not from
the river, they were imported
from Norway. Most of the
“yule” stone (local vernacular)
has been picked up from along
the tracks to be repurposed for
walkways or inlaid in decora-
tive masonry beams, but you
might get lucky and find some
Y ule stones used to crush guayule plant-photo courtesy of U.C . Berkeley, Bancroft
Library
like a piece of birthday cake in
the roadcut. Use a hand-held
magnifying glass to see the
hard, dense, and sharp silica
formed from tiny bodies of
marine sponges (the spicules
which have been overlooked.
According to Dennis T. Ray,
author
of
the
1993
continued on page 16
Cenizo
Second Quarter 2018
15