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Sunset in camp.
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I noted in the last posting that we were in the holiday
time of the year and presented my Christmas “wish list.” We had zoomed past
Halloween and the pumpkins and broom-riding characters. The orange pumpkins
represent the bounty of the fall harvest and the orange fires lighting up the
darkening night sky. The Celts and
Druids visited their spirit world ancestors around Halloween (All Hallows Eve) while
many Christian religions celebrate All Souls Day and All Saints Day at about
the same time. Spirit worlds are dark
and black as are “witches”, black cats, black bats and black spiders. My favorite orange of Halloween is associated
with candy corn!
Before the masks were off the discount shelves we slipped
into a purely American holiday, Thanksgiving. Here we celebrated the bounty of
the harvest, especially yellow corn, perhaps the most staple grain during all
episodes of U.S. history. The orange
pumpkins were still around although various “punkin chunken” contests certainly
helped delete the supply. Brown is often
associated with the holiday since most fall and late winter leaves are sort of
this drab color.
On or about December 22nd or 21st the Winter Solstice arrived
in the Northern Hemisphere: the sun reached its most southern position directly
above the Tropic of Capricorn, (~23.5 degree south), and the days were short
and dark.
A few days after the Solstice, the traditional
Christian-celebrated Christmas arrived on December 25th. The colors most associated with Christmas
seem to be red and green (with white a distant 3rd) although in the
modern world blue, silver and gold are thrown into the mix. Since Christmas in the northern hemisphere
arrives during the often bleak, drab and gray winter, early European
civilizations brought sprigs of greenery, for example pine boughs, into the
house as a way to cheer up the inhabitants.
Even better would be a find of holly with red berries. As a substitute for holly, early Christmas
trees were decorated with red apples.
White represents the external world of snow.
Now, there also are a number of Christian religious
reasons for the red, green and white used at Christmas; however, I will not
delve into those issues.
Things just sort of chugged along with Christmas
colors and an elf-like, dour Santa until 1930 when an illustrator by the name of
Fred Mizen was hired by the Coca-Cola ® Company to create a happy Santa
drinking a bottle of coke ®. That first
happy Santa was used as advertising in the December 1931 edition of the
Saturday Evening Post. The image was a big
hit with the public so Coca Cola hired, in 1931, an illustrator by the name of
Haddon Sundblom to create new Santa and Coke images on a yearly basis, That relationship lasted for 35 years as
Haddon created a jolly, plump and happy, older Santa Claus. Haddon
dressed his Santas in red and white to match the advertising colors of Coca
Cola, his employer. Red and White were
also the colors of robes worn by Christian bishops. Haddon evidently also borrowed from Clement
Moore’s 1822 poem, A Visit from Saint
Nicholas—you know, Twas the night before Christmas and all
through the house… chubby
and plump, a right jolly old elf.
So today, a non-religious Christmas celebration is
usually represented by a green tree (pine, spruce, fir) and a red and white
Santa. Sundblom’s Santas radiated warmth
from a grandfather like person, one who loved children and so snacks were left
behind by the nice kids. Almost any
person of my age living in North America would recognize Haddon Sundblom’s
rendition of Christmas Santas. Coca
Colas advertising was a stroke of genius and as a boy I always looked forward
to seeing the newest editions and would ask my father to please bring home a
coke along with an advertising poster.
So, what does all this banter mean when it comes to
minerals? Probably nothing but as the
days got shorter and darker I sometimes lounged around thinking how to relate
minerals to some sort of a story. After 328
postings I sometimes lose my concentration, but not on this one---what would
make good Christmas minerals, related red and green combinations? So, I started putting this little offering together
but was waylaid by a number or other opportunities---like spending time with my
family in a condo at the Colorado ski slopes.
Now, I don’t downhill (love x-country) but sitting by a fireplace with a
good book is a great way to spend an afternoon/week and so it was, and the beginning
of 2019 arrived and disappeared. By then
it was time to begin packing my 5TH Wheel for a visit to the Tucson Gem
and Mineral Show making certain to arrive in mid-January for a camp near the
Superstition Mountains in Lost Dutchman State Park. So, here I am still thinking I need to get
this post out!
In my way of thinking, the perfect Christmas “mineral”
would not be a single mineral but a semi-precious gem called ruby zoisite,
ruby-in-zoisite, or anyolite. Specimens
are composed mostly of the green mineral zoisite (chrome variety) accompanied
by opaque dark red ruby crystals and often by black crystals of the amphibole
pargasite (formerly identified as the hornblende amphibole tschermakite). Anyolite specimens are commonly used to make cabochons,
beads, tumbled stones and sculpted objects (elephants seem to be a favorite). But
any way you look at it, the red ruby presents a great contrast to the green
zoisite—the perfect Christmas stone!
Zoisite is a calcium aluminum silicate [Ca2Al3(Si2O7)(SiO4)O(OH)]
that would probably be unfamiliar to most people except for a single gemmy
variety. Most zoisite seems nondescript
and occurs in a wide variety of shapes from massive to prismatic crystals. The elongated crystals that belong to the Orthorhombic
Crystal System are perhaps the most common and they are striated along the
C-axis (the long axis). Zoisite crystals
also commonly radiate out from a center with the entire mass forming a “circle”
(two-dimensional view). Crystals occur
in a variety of colors from red and pink to green and blue to brown or
gray---take your choice. In anyolite the
tiny zoisite crystal have a green tint imparted by trace amounts of chromium. Zoisite
is fairly soft (as a gemstone) and is usually stated as 6.0-6.5 (Mohs). It is brittle, transparent to translucent to
opaque, and can have a vitreous to pearly luster. It is found in a wide variety
of environments ranging from contact metamorphic rocks to regional metamorphic
schists to granite pegmatites. It seems
to be one of those minerals that is tough to pin down.
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| This beautiful emerald-cut tanzanite ring is offered for sale by Diamondere Inc. The total caret weight is 4.97 and the price is $8277. Photo courtesy of www.diamondere.com. |
As I stated above, who would recognize zoisite except
for the sought after gemmy variety tanzanite!
Discovered in the late 1960s in Tanzania, tanzanite can be a beautiful
blue color and is a giant hit on the gem market ranking only below sapphire as
the most popular blue gemstone. The blue color in tanzanite is produced by trace
amounts of vanadium; however, the natural deep blue gems are scarce and today
most gems are produced by heating brown or green tanzanite to a temperature of
~600 degrees C when the oxidation state of the vanadium changes and the blue
color is emphasized. Tanzanite gems are
graded similar to diamonds—clarity, color, size, and cut. The cleaner (no inclusions) and bluer the
stone the higher the value. Good cuts
require numerous facets to bring out the brilliance. These good stones bring prices of thousands
of dollars per caret. For a great series
of articles on the grading of tanzanite gems check out the series of articles
by Lapigems at http://www.lapigems.com/Articles/Tanzanite-Color-How-it-Affects-Value.aspx.
Tanzanite is one of the most popular gemstones on the
market but is rare as all stones are mined from about 8 square miles in an area
around Mt. Kilimanjaro in Tanzania. It might have remained a minor gem after
discovery if Tiffany and Company had not put on an advertising blitz to get the
public interested in this great new gem!
The blitz worked and today the company TanzaniteOne mining Ltd. Is the
major player and seems to have a huge influence of the price (as does the
government of Tanzania, and natural disasters such as floods).
So, if zoisite, other than tanzanite, is relatively
unknown then ruby, the other main constituent in anyolite, is one of the best
know gems. In fact, ruby may be the most
popular, and the most expensive, of the colored gemstones (others argue for gem
emerald, a green beryl). A clear, large, pigeon-blood red, and well-cut ruby
can bring thousands of dollars on the gem market. Unfortunately, the ruby in anyolite is
fractured and nearly opaque and therefore of non-gem quality. However, it still contrasts nicely with the
green zoisite and is very showy in cabochons.
Ruby, an aluminum oxide, is
actually a variety of the mineral corundum (Al2O3) where
minor amounts of chromium provide the red color. A second variety of corundum is the multi-colored
gem, sapphire, colored by minor amounts of titanium and iron. The most valuable
sapphires are corn flower blue in color; however, several other colors of
sapphires appear on the market. Any
colored corundum that is not red is a sapphire.
Corundum is a name that is well known to beginning
geology students as it occupies #9 on the Mohs Scale of Hardness—sandwiched between
#10 diamond (the hardest) and #8 topaz. Corundum
can be found in both metamorphic and igneous rocks that are silica-poor but rich
in aluminum. However, the mineral is so hard that many of the gemstones are
panned from alluvial gravels as the remains of eroded parent rocks. Crystals are often six-sided, tapering,
hexagonal dipyramids. Both gem sapphires
and gem rubies generally come from southeast Asia.
The third component of anyolite is the amphibole
pargasite, a sodium calcium aluminum magnesium silicate. Actually, pargasite is a group name with
several modifiers to indicate a dominant element. I presume that the anyolite black (actually
very dark green) pargasite indicates the presence of iron. In a previous post (2/16/15), the pargasite I
described from Pakistan was a a nice green color, perhaps with minor amounts of
chromium?
I purchased my specimen of anyolite a couple of years
ago at the fall Denver Show. It was
collected from the major anyolite locality in Tanzania, the Mundarara
Mine. MinDat also reports a minor
collecting locality near Drosendorf-Zissersdorf, Austria. As best I can determine, anyolite is the
product of metamorphic activity.
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Anyolite or ruby-in-zoisite. The zoisite, (Z) is composed of tiny prismatic crystals. Pargasite (P) crystals are larger (up to 3 mm) while the ruby (R) is badly fractured. Width of photo ~10 cm.
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So, there it is—the perfect Christmas rock. But now it is 77 degrees here in the desert,
the sun is shining, a jolly old Santa seems ages ago and the length of daylight
has increased 21 minutes since the Solstice. The
Tucson shows are just two weeks away –happy days are here again!
