#Fluorescent granite
19 messages in this thread
Doug,
In mid August at the FM gathering at Washington Pass, WA, I should be able to
find you a specimen of the alkaline grainite in which the fluorescent
zektzerite is a rock-forming mineral; question, what size specimen do you
prefer? Tons is possible, but not practical.
Any other collectors of fluorescent minerals who would like a specimen, I am
willing to gather and send them for the shipping cost.
Lanny
> Any other collectors of fluorescent minerals who would like a specimen, I
> am willing to gather and send them for the shipping cost.
I'd go for that – golf ball sized or smaller.
Thanks, Guy
P.S. I'm thinking about vacation plans in that timeframe… maybe I could
come up and find my own specimen…
Guy
Definitely come on up and join the fun, drink (your choice) around the
campfire, tell stories, learn about new localities from FM members/collectors,
do a little trash pickup, collect some interesting and rare minerals, have a
lot of fun. That is the nights of August 12th & 13th, the clean up is Saturday
morning, all other time is free to collect.
Send a note to Cheryl so she can reserve enough camp spots, it is the Klipchuck
Cpgd, east of Washington pass on Hwy 20, about 3.5 miles W. of Mazama. Contact:
Cheryl Burnell
PO Box 77
Ocean Park, WA 98640
Hi, Lanny
I'll get together with my boss next week and see if I can at least get
Friday, August 12th off for the drive up and I'll let you (and Cheryl)
know. Sounds like fun.
Thanks, Guy
P.S. I actually found my way to the top of Tator Hill (a minor landmark in
S. Columbia county) this afternoon – thanks to the Scout. My prevous trys
had always left me lost in the 'maze'. This was an acid test. No maps, no
compass, just the location programmed into the Scout from a topo map hanging
on the wall at home. My decisions at the forks in the road were made based
on the Scout in NAV mode. 🙂
Hi, Lanny (and Michael)
I'm confirmed for the trip, assuming the unspeakable doesn't happen between
now and then – hey, I survived the 4th without burning myself! Klipchuck CG
is programmed (227.1 miles @ 29 degrees). 🙂 See you there.
Thanks, Guy
P.S. I'll get a note off to Cheryl tomorrow…
Guy,
Great, see you there. I would recommend that you use I-5 and Hwy 20, not your
Scout to find the route to the Cpgd!
Lanny
Guy – I am scheduling my time to coincide with the clean-up activities that
Lanny has mentioned earlier. If you should be able to get up this way, I would
greatly enjoy meeting you.
Michael
Hi, Michael
See my reply to Lanny.
> If you should be able to get up this way, I would greatly enjoy meeting
> you.
Likewise, I'm sure. 🙂
Regards, Guy
Hi, Lanny–
That zektzerite would be much appreciated. Roughly 2 inches would be ideal; I
am not fussy about that.
Is the zektzerite abundant in granites throughout a wide area, or is it a few
scattered pips in one small outcrop? Aside from a dull maroon fluorescence
from microcline, I do not recall any fluorescent minerals in a granite. I find
myself wondering what was unique about this granite's formation that led to
inclusion of the obscure and fluorescent mineral, but I am visiting CA this
weekend and my references are not handy.
–Doug
Doug,
It is an alkaline granite with a lot of zirconium in it along with some REE
making it a wonderful breeding ground for some uncommon and rare
minerals–zektzerite-okanoganite-calciohilairet (type locality for these 3),
gagarinite, kainosite, gadolinite, basnaesite, pyrochlore, and others.
Strangely, the zektzerite, which forms very fine euhedral crystals in
miarolitic cavities (up to 3.8 cm) also occurs as grains in the rock. When you
find an area that has zektzerite crystals, the rock around it typically is
loaded. The alkaline phase of the granite is restricted to several high
elevation spots, but collecting in situ has been nearly useless (even for
mountain climbers) nearly all collecting is done in boulders in three main
talus slopes and a few obscure spots. Most people (obviously not interested in
nasty climbs in steep talus or cliffs–not quite requiring gear) do their
collecting along the highway in the talus. I've found my best zektzerite (to
1.5 cm) by hiking across country into some really steep country and checking
out the boulders there. I've found very little zektzerite in the roadside talus
but have seen some very nice specimens collected by others just a few feet from
their car!
Lanny
Hi, Lanny–
This alkaline granite rich in Zr and REE sounds like it should provide a
number of fluorescent minerals, more than I have heard about to date from WA.
The rare earth elements in particular are likely to figure as activators of
fluorescence, and fluorescent minerals seem to turn up in alkaline igneous
rocks more often than the common high-silica kind. I wonder if the alkalinity
shares a common cause with the increased presence of rare earth elements.
–Doug
Doug,
It's not that alkalinity per se and rare earths get along together, it's that
the typical geomorphic carrier of rare earths is fluorine. And, the halogens
and alkalis are both substantially volatile moeities, so they tend to end up
together in rocks (or seawater!).
The rare earths don't segregate as much as many other minerals because their
ionic size is so similar. The lattices they fit into tend to be sized
according to their anions, so you fit in one rare earth, you can fit in any of
the rare earths. With other elements, the lattice is skewed or distorted,
hence the Gibbs molar volume energy is slightly different. On the surface, we
don't see much segregation, but when you multiply those small energy
differences by a megabar, they all of a sudden aren't so small and minerals
tend to differentiate.
We have a large rhyolitic dike in the northern part of the Llano uplift that
has some large phenocrysts of silica, heavily doped with the heavier rare
earths. It fluoresces a brilliant blue-green, with a substantial yellowish
green phosphorescence – two or three seconds at least. Moreover, the silica is
blue in incident light, the result of radiation damage from paleozoic zirconium
and promethium. Most of the zirconium, however, is in the form of itty-bitty
zircons, spread around through the biotite.
— Norm
Hi, Norm–
I'd love to get a sample of this rhyolite with fluorescent silica phenocrysts.
Can you be more specific about where one obtains some? I am also curious as to
which silica mineral it is – quartz?
Blue is mildly surprising as a daylight color caused by radiation damage; I
expect black (or brown) smoky quartz normally, or with some ferric iron
present, the purple of amethyst. The radiation may be reacting with some other
impurity in the quartz to get a blue result, perhaps an unusual impurity like
some rare earth element.
–Doug
Hi Doug,
Just returned today from making another trip to overload my basement with
incredible mineral specimens (i.e. junk). There is nothing else of fluorescence
of any significance that I am aware of at Wash. Pass. I expect that the
alkalinity of the grainite is a factor in the REE stuff, as I recall, other
alkaline granites in the world also produce a lot of REE minerals and rare and
unusual stuff.
As for fluorescent minerals from Washington, there are more than are reported.
For instance, are you aware that some quartz in many of the "famous" Washington
quartz localities fluoresce with yellowish white phantoms?
Lanny
Hi, Lanny–
I have in my database quartz with fluorescent hydrocarbon inclusions from
Snohomish and Ilwaco in WA. Are we talking about the same stuff? I have a
quartz crystal with similar-sounding hydrocarbon phantoms from Asturias, Spain.
Hydrocarbon inclusions can be quite fascinating to inspect with a microscope,
at least when of the right size in a small enough or thin-sectioned specimen.
Changing the focus causes new ones to "appear" as others "disappear"; they may
form patterns such as a line "marching" across the field of view when they are
following cleavage planes or some such.
P.S. I have finally acquired a 2nd CIS account and requested a subscription to
rockhounds mail-list; I figure to include traffic from that list in my weekly
postings in the library.
–Doug
Doug
No, not the same thing. These phantoms don't have anything obvious that makes
them evident. The crystal can be completely clear under white light and contain
one or more phantoms under UV. They occur in several of the localities, just a
few here and a few there. I am going to run the light over my collection and
extras and see what I come up with.
Another interesting occurrence and apparently unusual are the topaz xtls from
the Sawtooth Mtns in Idaho. Quite a few of them have a fluorescent (yellowish
to creamy white) zone under UV in the middle that under white light is a milky
zone in an amber/sherry xtl.
Do you have any fluorescent stilbite? I discovered a deposit of them last year.
Gee, more rockhound mail-list messages to read. I am going to have to wean
myself from CIS pretty soon or get nothing else done! Speaking of that, I just
downloaded your RM0021. Did 20 get lost somewhere?
Lanny
Hi, Lanny–
Actually I failed to mention that the Asturias quartz phantoms are invisible
in daylight to my unaided eye, being clear only under UV. I had more or less
expected to find hydrocarbon inclusions become visible under the microscope;
since I did not, maybe it is something other than hydrocarbons doing the
fluorescing in this case (a Min. Rec. article on Asturias mentioned hydrocarbon
inclusions, and I think mentioned they were fluorescent, but told of no
fluorescent phantoms).
I have a topaz crystal from "Centerville, ID" much like you describe; it is
indeed a special specimen to me.
Fluorescent stilbite seems uncommon. I have one with a dim bluish fluorescence
and a one of the tiny solitary bright-green-fluorescing pips I find on a number
of specimens from many places, always wondering if it is willemite dust from
other specimens that got stuck there or some such. Are your stilbites more
impressive under UV?
I made up RM0020.ARC last week, but it is not in the library. My job has been
eating too much of my brain lately; perhaps I simply failed to upload it after
readying it. Anyway, I am uploading it this pass, so hope to find it in the
library tomorrow.
–Doug
The best fluorescent phantoms in quartz I have are from Green Ridge, apparently
some quartzes from other King Co., WA localities fluoresce but I didn't notice
any in a quick check of my mineral drawers. Those that fluoresce from Green
Ridge typically show multiple phantoms but under white light there is nothing
or may be some milkyness–but not showing a phantom. The fluorescent color is
yellowish. The locality is a breccia pipe in a diorite batholith and the quartz
is hydrothermal.
The stilbite fluoresces a creamy color on edges and sometimes on a main "prism"
face. These are slightly weathered and don't appear to be coated with anything.
The stilbite is typically on a tiny quartz druse on a bluish agate. Amongst the
quartz, spots of something fluoresces bright yellowish but it is not obvious
what is fluorescing.
Looking at these, going over my collection I have found a lot more fluorescent
calcite than I was aware of–some nice light oranges, creamy colors, reddish
colors, etc. Nice stuff! Also discovered something I had forgotten–a lot of
microcline fluoresces bright red!
Lanny
Hi, Lanny–
Your discovery of fluorescent minerals in your collection is familiar to me;
going over my collection with a powerful shortwave UV lamp for the first time
turned up a lot of fluorescent minerals I had not known I had. As a youngster
I had only a dim longwave UV lamp, and collected a lot of minerals I thought of
as non-fluorescent at the time. I suspect any mineral collector who has not
tried UV lamps on his collection has a few surprises waiting.
"a lot of microcline fluoresces bright red" is a somewhat surprising to me. I
have often encountered granites with microcline that fluoresces a dull maroon,
and have heard of bright-blue fluorescing microclines occasionally. Of course
brightness is in the eye of the beholder – if you are going over a lot of dimly
or non- fluorescent specimens with a powerful lamp in total darkness, the
microcline fluorescence may indeed seem bright. I think of it as dull because
I often see it after looking at Franklin calcite or some such. Are we talking
about the same thing, or is WA microcline special?
–Doug