In a previous posting I noted that a two-day excursion to the Tucson 2021 Redo was enjoyable and I came home with a few treasures! Of course, I consider most of my buys as treasures although a few stinkers appear now and then. Remember, as Bob Jones coined the term, I am a frugal collector. I purchase less expensive specimens that “make me happy.” I am not collecting for exhibits, or even local mineral shows, but for specimens that I can study and learn from. Being a life-long learner is a high priority in my life! Life is too short to be anything but happy.
Happiness, true happiness, is an inner quality. It is a state of mind. If your mind is at peace, you are happy. If your mind is at peace, but you have nothing else, you can be happy. If you have everything the world can give - pleasure, possessions, power - but lack peace of mind, you can never be happy. Dada Vaswani
Living in the Plains, Midwest, and West over the
decades, I am not overly familiar with the geology of the Appalachian chain of mountains. Oh, I have driven through and
camped several times, I can spout off the creating orogenic events, and the
physiographic provinces, etc. but outside of a few famous collecting
localities/mines I remain a novice learner when it comes to the minerals. That is one reason I enjoy the professional,
but semi-hard core, journals like Mineralogical Record and Rocks and
Minerals. I joined the Baltimore Mineral Society to get a non-western U.S.
perspective on geology and minerals and now read several eastern mineral club newsletters
if they are available on the Web. Life
is interesting.
I went
to the woods because I wished to live deliberately, to front only the essential
facts of life, and see if I could not learn what it had to teach, and not, when
I came to die, discover that I had not lived. Henry David Thoreau
At the Show I was able to pick up a hunk (5 cm. X 8
cm) of mostly native copper with a little calcite and perhaps a few other
minerals. It had been cleaned with acid so the copper would show and looked
like the nuggets from Michigan that originally had been released from the
Precambrian basalt by Pleistocene glaciers.
However, my purchased specimen came from the Blue Ridge portion of
Pennsylvania, a state that I did not realize produced copper. The Pennsylvania
Geological Survey noted that a small area (about 1- by 5-mile belt) contains
trace- to minor amounts of native copper in Adams and Franklin Counties and my
specimen was labeled as collected from Pine Mountain, Adams County. This is a
general location of native copper deposits lying west of Blue Ridge summit. MinDat notes the presence of native copper in
epidotic rhyolite, massive quartz and associated secondary copper minerals. No specific quarry or prospect was noted with
my specimen. Unlike the Michigan nuggets
that were released and transported by glaciers, the Pennsylvania copper belt
fell ~35 miles short of glacial activity so copper nuggets were never released
from their enclosing metabasalt (part of the Precambrian Catoctin Formation). The
Pennsylvania Geological Survey has identified eight named mines, and numerous
small prospects, that are known in the native-copper belt, but production has
always been minimal. Unlike many copper deposits in the western U.S. that are
associated with intrusions and hydrothermal activity, R.A. Landy, in a 1961
unpublished Ph.D. thesis at Penn State, believed[M1] that
the native copper deposits were developed from the rearrangement and
reconcentration of the copper originally present in the rock itself (the
metamorphosed basalt). The original
basalt came from flows resulting from crustal expansion in the late Precambrian—continents
or proto-continents pulling apart.
I also picked up four specimens from Lehman Minerals,
collectors on the opposite side of the country—the White and Inyo Mountains of
California. Chris Lehman is
headquartered in Bishop, the only city in Inyo County and situated at the head
of Owens Valley between the Sierra Nevada (on the west) and the White Mountains
(on the east). The Whites are
interesting from several points of view including the presence of Late
Proterozoic (latest Precambrian) rocks that represent sediment shed off the
early North American (in today’s geography) continent. These rocks confused geologists for decades
as they often contained fossils older than the Cambrian trilobites (and
commonly were soft bodied). Were they
Cambrian in age? Or Precambrian? They were often referred to as being Eocambrian
in age, but stratigraphers finally settled on Ediacaran (see Posting April 13,
2017) for that particular period of time.
Above these Precambrian rocks is a thick section of
mostly shallow water marine sedimentary rocks of Cambrian (a continuation from
the Ediacaran) and Ordovician age. However, the Ordovician sedimentary rocks,
along with a thick section of later Mesozoic metasedimentary and metavolcanic
rocks were brought into the Whites (current geography) from the northeast
sliding along large scale thrust faults.
Geologists call these foreign rocks allochthonous rocks. This turmoil continued and in the Mesozoic
all sorts of crap broke loose as the Pacific Plate and others (mostly
microcontinents) were banging into the North American Plate with the former
being subducted beneath the latter (although some western rocks were stuck onto
the North American Plate). The
subduction, with later heat and melting at depth, resulted in large scale
plutonic events (magma rising towards the surface but cooling and crystallizing
before reaching the surface). Such was
the case in the White Mountains but to the west the Sierra Nevada plutonic event
was even more massive as these mountains are much larger that the White
Mountains. The collision of these plates
rippled across western North America creating orogenic events as it
proceeded. The Cenozoic was marked by
two major “happenings”: massive volcanism, especially in the mid to late
Tertiary; and the crustal extension resulting in the creation of the fault
block mountains of the Basin and Range.
In fact, the White Mountains are the westernmost range of this
physiographic province.
The above explanation of the geology of the White
Mountains is not very understandable and is critically short on details. However, there are hundreds of professional
papers scattered in libraries, and sometimes on the Web, that would be tough to
synthesize in a posting like this. The
geology is complicated!
I have
yet to see any problem, however complicated, which, when looked at in the right
way did not become still more complicated.
Paul
Anderson
Chris Lehman has a collecting locality east of Bishop
that MinDat refers to as the Lehman Anatase Prospect. I am fairly certain two
of my four specimens came from that location; however, the other two specimens are
listed as from the “White or Inyo Mountains.” I
suppose they are proprietary locations.
One specimen from the Lehman Prospect consists of
water clear and terminated quartz crystals arranged in a spray. The anatase occurs as inclusions within the
quartz with additional anatase crystallizing on the exterior. The Quartz Page
defines three types of inclusions in quartz: 1) Protogenetic where the minerals
formed before the quartz and were engulfed by the growing quartz; 2) Syngenetic
where the inclusions and the quartz grow simultaneously; and 3) Epigenetic where
during the growth of the quartz crystal there is a pause that allows new
incompatible elements into the crystal structure. The specimen from the Lehman shows syngenetic
crystals of anatase embedded in the quartz and are termed phantom crystals.
Water clear quartz crystals mounted on a pin (white). Note anatase inclusions and external growths. Length of largest quartz crystal ~1.2 cm.
A second specimen from Lehman is a larger quartz
crystal covered with quite tiny greenish brown crystals of anatase with a few
crystals of adularia (potassium aluminum silicate). The large crystal may also be included;
however, the exterior growth prevents peeking into the quartz.
Green anatase crystals ~.5 mm, or less, in length.
Anatase is a titanium oxide, one of three polymorphs of TiO2—the other two being rutile and brookite. There seems to be at least three other forms of titanium oxide that were identified in meteorites and therefore are exceedingly rare. Anatase is the least stable of the polymorphs and forms at lower temperatures and at later stages in crystallization, often associated with quartz and adularia. Belonging to the Tetragonal Crystal System, anatase usually appears as tabular or “double pyramid” crystals and are usually “green” or brown (although crystals may have a variety of colors). It has a metallic luster is essentially opaque with a hardness of ~6 (Mohs). Titanium oxide is mostly found in metamorphic rocks and pegmatites.
The small adularia crystals [KAlSi3O8]
belong to the Feldspar Group and actually are a low temperature variety of orthoclase
(a potassium or K Feldspar). Adularia
crystals commonly are glassy and transparent and often tough to identify unless
they have a moonstone sheen and play of colors.
A third specimen is from the nearby Inyo Mountains and
is a single, prismatic, pretty ugly, crystal of epidote [(Ca2)(Al2Fe)(Si2O7)(SiO4)O(OH)]
with an attached tiny, twinned crystal
of titanite, a calcium titanium silicate
(CaTi(SiO4)O), formally called sphene due to its wedge shape. Crystals have an adamantine luster, are
translucent to transparent with a white streak and a hardness of ~5.5
(Mohs). It appears in igneous and
metamorphic rocks. Not an exceptional specimen but one that is interesting with
the attachment.
The 4th Lehman specimen is a group of vesuvianite crystals on a matrix of grossular (Garnet Group). The vesuvianite [Ca10(Mg,Fe)2Al4(SiO4)5(Si2O7)2(OH,F)4] forms beautiful crystals that are either long prismatic and columnar, or short pyramids, with a greenish yellow to yellow brown color. They have a vitreous luster, are brittle and fracture easily, and a hardness of ~6+ (Mohs). Most crystals on this specimen are fairly translucent. Vesuvianite usually form in skarn deposits (limestone subject to contact metamorphism). See a previous Posting, November 18, 2012, for additional information.
Mass of grossular garnets. Width FOV ~6mm.
Grossular is a calcium aluminum silicate [Ca3Al2(SiO4)3] that often is some sort of a green color since it is named for the color of gooseberries. It is a common mineral in contact metamorphic zones associated with limestone, and is an associate of vesuvianite, wollastonite and diopside.
The saddest aspect of life right now is that science gathers knowledge faster than society gathers wisdom. Isaac Asimov
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