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Fresnoite - A Rare Barium Titanium Silicate from California
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by John Veevaert, Trinity Mineral Co.
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In October of this past year, I was headed back home to Weaverville from Los Angeles and decided to make a detour to San Benito County for a quick hit (mineral collecting) at a few locales that I knew of. Actually, I had nothing to do with it as my
vehicle has an automatic pilot of some sort, such that, when it and I are within 100 miles of San Benito County it just "goes there." I am powerless to resume control until a certain quantity of rocks have been dislodged and relocated in the back of my
vehicle.
For those of you who have never ventured into San Benito County it is unquestionably one of those places that gives you pause for reflection. Less than 100 miles from San Francisco, it is largely an empty piece of real estate tucked away in the coast
ranges of central California. Lots of narrow roads, remarkable scenery, and few services anywhere except in the few large towns that exist such as Hollister. You never know what to expect, so when I go I do not plan any outcomes. This trip was no
exception to the rule as along the windy road, I encountered something that I would not have believed had I not seen it with my own two eyes: a herd of ELK crossing the road between Coalinga and Clear Creek at around 9:30 pm! I am not kidding you here!
They were either Elk or giant deer mutations! Well, enough of the Twilight Zone and back to the rocks...
I pulled into the Clear Creek Management Area -- an important name designated by the BLM for a place that is overrun by motorcycles and other environmentally destructive off road vehicles -- at around 10:00 PM after having "decided" (see above) to go to
the area and do some mineral collecting.
"What in blazes?" you ask, "are you doing at 10 PM when the sun is long gone and it is still hours and hours till daylight ~and~ you are heading up a funky dirt road to one of the more remote areas in California? FRESNOITE is what is driving me! (see
figure 1).
 | Figure 1 - Specimen of yellow fresnoite from the Junnila Mine. The crystal is 1.1 cm across and is exposed from analcime
matrix. |
Fresnoite is a very rare mineral named after the county that it was found in: Fresno County. The location of the discovery is very close to another famous mineral location in southern-most San Benito County. Its composition is Ba2TiSi2O8. Hmm, you say.
That looks very close to another mineral with a composition of BaTiSi3O9 that goes by the name of BENITOITE (see figure 2).
 | Figure 2 - specimen of benitoite from the Benitoite Gem Mine. The largest crystal is 2.2 cm across and incrediblely
gemmy! |
Fresnoite, like benitoite, is brightly fluorescent under SW (short wave) UV light. That, however, is about where the similarity ends between these two minerals. Benitoite, which is also my favorite mineral species, is probably one of the more famous
minerals in the world owing to many unique and rare characteristics.Most noteably, its marvelous, simple and unique triangular shaped crystal form and that deep sapphire blue color!
As mentioned above, fresnoite is brightly fluorescent under short-wave ultraviolet light. It fluoresces a bright, very light blue color. In white light it looks a lot different than benitoite with a white to yellow to pink color, while benitoite is
either a deep blue to white color (see figures 3 and 4).
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| Figure 3 is a photo of white analcime with a light pink colored crystal fragment shown in white light. The arrow points to the fresnoite. |
Figure 4 is the specimen shown in Figure 3 under SW UV light. |
Fresnoite also forms tetragonal crystals while benitoite is in the hexagonal crystal system.
Back to the story. I pulled up to the site at about 10:30 PM or so, and was greeted by a very bright 3/4 full moon. Ooops! I hadn't thought to check the lunar schedule before pursuing this trek (editorial note: this sort of thing always happens when you
succumb to spontaneity!). I had a 4watt SW lamp with me that under completely dark conditions can do OK - by that I mean that one can find fluorescent minerals without having to do much more than hold the lamp at slightly below waist level. With the 3/4
full moon I was literally awash in white light! You would be amazed at how bright it can be outside where you are 50 miles form the nearest artificial light source and the landscape is light colored to begin with! This meant having to follow my moon
shadow in a stooped position.
Initially I was singing my two favorite tunes: "So close and yet so far" and "Poor, poor pitiful me". Shortly, though, I came out of my "pity pot" syndrome and set out to do what I had come for: The removal of rocks containing fresnoite! I took myself,
my 4 watt lamp, my hammers and chisels, and my 40 year old back and started to crawl over everything. Remember: it is after 11:00 PM by now and it is nighttime. I found a couple of pieces of scattered fresnoite initially, then hit a dry spell that
lasted long enough for me to decide to go to the benitoite zone and rustle up a few pieces of that stuff (Benitoite is found at the Junnila mine and three other locations in San Benito County including the famous Gem Mine). Actually, benitoite is fairly
common at this locale. It is just not of very high quality... but it is still benitoite as seen in the fluorescent photo!!! (See figures 8 and 9). By now it was pushing 11:45 PM and I decided to make my way back up the cut face and probably leave with
my mere 10 pounds of rocks.
As I was making my way up the side access road, I noticed a bright fluorescent reaction from about 3 feet away from my lamp - the unmistakable fluorescence of fresnoite. I got up enough courage to ask my back to stoop one more time and this time.... It
was worth it! I found a nice 1.1 cm exposed crystal of fresnoite in situ! Suddenly, I was 19 all over again. The sore and stiff back melted away into the recesses of my small mind and I narrowly focused my attention on following this "show" with all
the careful precision of a skilled surgeon operating on someone's diseased brain. Now that is a bunch of hooey! I was slamming my hammer one blow after another with the lamp in my mouth waiting for one bright fluorescent crystal after another to become
exposed. Seconds slipped into minutes, minutes into hours and before I really had time to grasp what I had done, there was a new 5 x 3 x 2 foot hole in the earth compliments of my hammer, chisels, pry bar and me! The only break I took was to run back up
to my vehicle and grab new batteries for the SW lamp then race back down and resume my excited removal of rocks containing fresnoite. Next to the new hole was a pile of "keepers" containing fresnoite crystals and partial crystals. It was now pushing
4:00 am and despite the constant surge of adrenaline, I was definitely getting ready for "La La" land.
Still, though, I wanted to be sure to make sure that I had wrapped up only rocks containing fresnoite so I spent the next hour waving my lamp over the pile and carefully wrapping specimens with newspaper and paper towels. I was also taking in the world
between the hours of 4 and 5 am. This was the first time I had ever gone collecting like this and it is amazing how quiet the world is at night. Several times I stopped what I was doing to look across the landscape from where I was working on top of the
knob and was struck by the calm of the place. Occasionally a jet would fly by with its delayed sound. Other than that. the only noises I can recall were the clanging of my hammer and chisel on the rocks and the ridiculous song that was stuck in my head
which all too frequently came out of my mouth ("Ride, Captain, Ride, Upon my Mystery Ship" by Blues Image. Where the hell that came from is beyond me....) while I worked away. By 5:30 AM all was loaded in the car and I was ready - really ready - to take
a nap before heading on back up the road to my home in Weaverville.
I drove down to the bottom of the knob and looked for a secluded spot so that as the sun, which was only a couple hours away, wouldn't end up blasting my face with light. I was gone shortly after turning the engine off and reclining my car seat to as
close to a horizontal position as I could.
When I woke, I headed north for back home and was thoroughly excited at my great fortune. Fresnoite is an extremely rare mineral and only rarely is it found in any high quality crystals. My "haul" ended up containing 4 complete crystals and a mess of
broken or partial crystals and smears on matrix; in all, well over 200 specimens. It had been a great night to stay awake and sing a dumb song over and over again!!
The following are additional photos of fresnoite taken in white and fluorescent light.
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| Figure 5 is a specimen showing a partial yellow fresnoite exposed from the encasing analcime matrix. |
Figure 6 is the same rock as in figure 5 under SW UV light. |
 | Figure 7 is a specimen showing a partial yellow fresnoite exposed from the encasing analcime matrix. |
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| Figure 8 is a specimen of benitoite on matrix from the Junnila mine shown in white light. |
Figure 9 is the same rock as in figure 8 under SW UV light. |
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Copyright, 1997 by John Veevaert, Trinity Mineral Co.
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Trinity Mineral Co. sells quality mineral specimens including benitoite,
neptunite, fluorite, tourmaline and many others at very affordable prices
over the internet. There are many "Rooms" to visit at Trinity Mineral Co.
including a Micromount Room, local Fossil Room and the first mineral
specimen auction on the internet known as the Auction Room.
Drop in for a
visit and have some fun, or join the Online Mineral Auction!
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