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Identity HelpFluorescent Inclusion in Fluorite, Cave-In-Rock, IL

25th Nov 2015 06:08 UTCJacob Zonderman

this is an old piece from my late great-uncle's collection I got over a decade ago, the piece itself is probably 50+ years old. With the naked eye its visible, but hard to distinguish, can;t really get a good shot. Looks almost yellow naturally.

25th Nov 2015 11:06 UTCDavid Von Bargen Manager

Yellow fluorescence in fluorite is often petroleum inclusions.

25th Nov 2015 13:52 UTCJamison K. Brizendine 🌟 Expert

Jacob,

I answered a similar question last year in regards to hydrocarbon inclusions from the IL-KY Fluorspar District. (http://www.mindat.org/forum.php?read,11,342079,342098#msg-342098). This is a copy/paste response from then:

I was able to find a relatively recent graduate thesis paper and a few Economic Geology papers that specifically looked at the composition of fluid inclusions in the Illinois - Kentucky Fluorspar District:

Fluid inclusions are generally abundant in hydrothermal minerals from the Illinois- Kentucky district, particularly in fluorite. Hall and Freidman (1963) have estimated that fluorite from the Cave-in-Rock subdistrict can contain between 0.01 and 0.1 wt% inclusion fluid. Primary fluid inclusions are often intermixed within a dense tapestry of pseudosecondary and secondary fluid inclusions. Four types of fluid inclusions have been recognized in the district (Figure 3; Richardson and Pinckney, 1984).

Type I fluid inclusions constitute the majority and consist of an aqueous liquid and vapor phase. They can be primary, secondary, or pseudosecondary in origin and occur in all of the hydrothermal minerals. Fluid inclusions containing hydrocarbons are also abundant.

Type II fluid inclusions consist of oil and a vapor phase. The oil is typically yellow or brown in color and commonly contains dark spots of bitumen or degraded organic matter. Type II inclusions are typically round or oval in shape and primary in origin.

Type III fluid inclusions consist of an aqueous liquid, vapor, and liquid oil phase. Most are secondary or pseudosecondary in origin but some are primary. They are most common in fluorite but also occur in quartz and calcite.

Type IV fluid inclusions, which consist of aqueous liquid, vapor, and a daughter mineral were not observed in the present study. (Pelch 2011, pg. 18)

The photo above is from (Pelch 2011, 19) to help illustrate the fluid inclusions.

The wide variability in the homogenization temperatures may be due to the relative softness of the host minerals, making their fluid inclusions susceptible to variable post-entrapment stretching. Some of the discrepancies between the homogenization temperatures obtained in the present study and those obtained in previous studies may also be due to this stretching and that for many paragenetic stages only relatively small numbers of fluid inclusions are being compared. (Pelch 2011, 22)

Pelch (2011) came to the conclusion there was mixing of at least three chemically distinct fluids during the precipitation of the ore in the KY-IL District, one of which was rich in some metal (some of the fluid inclusions had a high aqueous ore metal concentration). Furthermore Pelch (2011) stated that the fluid inclusions had a high amount of iron and methane (the hydrocarbons), suggesting that the mineralizing fluids were in a reducing environment.

The paper had specimens from the following deposits: Hastie Quarry, Hill (Ledford) Mine, Minerva #1 Mine, M.F. Oxford #7 Mine and the North Green Mine.

References cited:

Hall, W., and I. Friedman, 1963, Composition of fluid inclusions, Cave-in-Rock fluorite district, Illinois, and upper Mississippi Valley zinc-lead district: Economic Geology, v. (58), p.886-911.

Pelch, M., 2011, Composition of fluid inclusions from the Cave-In-Rock bedded replacement fluorite deposits in the Illinois-Kentucky District: University of Missouri-Columbia, Master’s Thesis, 52 p.

Richardson, C. K., and Pinckney, D. M., 1984, The chemical and thermal evolution of the fluids in the Cave-in-Rock fluorspar district, Illinois: mineralogy, paragenesis, and fluid inclusions: Economic Geology, v (79), p. 1833-1856.

25th Nov 2015 17:01 UTCJacob Zonderman

The examples in that paper are tiny, mine is about 7x7 mm maybe a bit larger in one or more direction. I got a photo as best I could in normal light (adjusted the coloring a little to bring it out), it's right in the center where it is darker. Also, if this is important, it is associated with Galena.

25th Nov 2015 17:38 UTCMichael Sommers

Maybe witherite.

26th Nov 2015 02:59 UTCDennis McCoy

If I am interpreting your first photo correctly, you may have a fluorescent calcite inclusion in the fluorite crystal. The area of fluorescence is irregular and deep, so it is not likely to be the fluorite's response to UV.

Other areas that appear to be showing a response are along cleavage planes, and may be the result of damaged hydrocarbon inclusions which have migrated through the fracture plane. As others have noted, these fluorites are often associated with tiny (often fluorescent) oil filled voids. When these inclusions are damaged, the oils can migrate into cleaved planes and other areas of damage.

Another potential cause of a UV response along a fracture or cleavage plane is a repair. Some adhesives will fluoresce.

26th Nov 2015 05:14 UTCDoug Daniels

The two photos are confusing, specifically since they were taken at different angles, in different lighting. The first seems to be in both white light and UV light....yet, the yellow(ish) fluorescence shows within the fluorite, off the surface of the galena (lower left, first photo), and on the black plastic of the box; but the upper part of the photo appears as in white light. The second photo of the specimen is quite different - a pale purple, with apparently obvious galena at the bottom, but at a different angle of view from the first. I would go with petroleum inclusions, except for that yellowish appearance on the galena (?) at the bottom of the first photo.

26th Nov 2015 05:40 UTCJacob Zonderman

Underneath the Galena is some glue which can also be seen in the second photo. Here's a better photo in white light, I looked at it through a loupe but the faces are frosted so I couldn;t see enough detail to discern a shape. It has a sandy yellow color.

26th Nov 2015 21:58 UTCKeith A. Peregrine

Could be a number of minerals. Out of curiosity, I just checked my cabinet. Witherite (some very white), Strontianite, Barite, and Calcite all produce this creamy white fluorescence. Interestingly, there is variation in color within the same mineral ranging from white to creamy white to yellowish white. You will need to use another method to further identify your interesting fluorescent mineral.

27th Nov 2015 15:41 UTCReiner Mielke Expert

I don't know about everyone else but I cannot make out the shape of the fluorescent body. If it is cubic then like David said hydrocarbon inclusions. Hydrocarbon inclusions can give flourite it's color and fluorescence. They are so tiny you cannot see them with the naked eye but if there are enough of them it can make fluorite look brown. http://www.mindat.org/photo-253677.html In fact the browner the fluorite the stronger the fluorescence. Here is an example of fluorescence due to hydrocarbon inclusions http://www.mindat.org/photo-486889.html

27th Nov 2015 16:08 UTCBob Harman

There are now 7 responses to Jacob Z's original posting. All speculating about the various possibilities of a small area of fluorescence within his Illinois fluorite. It would help to know the original fluorite's exact mine location (probably the Harris Creek District: The Minerva, Denton and Annabel Lee Mines), as differing accompanying minerals and amounts of petroleum were found in some of the different mining districts. So, in fact and reality, there are these several possibilities and all our speculation about this small intracrystal area is just speculation and probably will really get us nowhere further. CHEERS.....BOB

27th Nov 2015 18:28 UTCJamison K. Brizendine 🌟 Expert

Bob certainly makes a good point, that without an exact mine or date, the only thing we can do is speculate until we are all blue in the face. That being said though, if you do ask the same question to 7 different people, doesn’t be surprised to get 8 different responses.

Let us assume that Jacob is correct that the piece was extracted 50+ years ago. Doing quick math that puts the extraction age in the middle of the 1960s. Remember that the Annabel Lee and the Denton mine weren’t open until the mid 1980s, so it being from either of these mines would be unlikely, if Jacob’s relative age of the specimen is correct. This piece does however; strongly resemble similar specimens from both the Hill-Ledford Mine and the W.L. Davis-Deardorff Mines, both having produced very similar fluorite and galena combination specimens and both were operating in the mid 1960s.

Does it mean that this specimen is definitely from either of these two mines? No, it is only my personal guess…

Second, baryte inclusions are typically seen in specimens that were golden or yellow in color from the Cave-in-Rock District. Both the Minerva #1 Mine and the Denton Mine produced specimens with these inclusions. There are probably other mines that had similar specimens with these inclusions, but they are the only ones with documented specimens, that I have personally seen. Too add fuel to this fire, the Elmwood Mine in Tennessee did produce baryte inclusions in purple fluorite, as well. But again, if the age is correct, that that probably eliminates the Elmwood too.

Thirdly, I personally have never seen a calcite, strontianite or a witherite inclusion in an IL-KY fluorite before…nor can I find an example on Mindat. Witherite was found in several Cave-in-Rock fluorite mines, but the best examples were from the Minerva #1 Mine. If there is an example of a witherite inclusion in a Illinois fluorite, I would certainly like to see one.

Finally, hydrocarbon inclusions can be visible to the naked eye from the Cave-in-Rock Distict. I personally own a fluorite with a visible hydrocarbon inclusion blob from the North Green Mine ( http://www.mindat.org/photo-652154.html ) .

My opinion still stands that this inclusion is caused by a hydrocarbon, not by another mineral.

27th Nov 2015 18:44 UTCRob Woodside 🌟 Manager

Inclusions can often be identified with Raman.

28th Nov 2015 03:17 UTCJacob Zonderman

Unfortunately the label only says Cave-In-Rock, IL and this was in the collection of my late great uncle who died about 15+ years ago. I don't think he collected passed the 70's maybe early 80's, so thats where I'm basing my age off of. Plus the label does not look much newer than the 70's. And from what I have gotten from many of the comments is that hydrocarbon inclusions look dark not light.

28th Nov 2015 13:10 UTCReiner Mielke Expert

Hydrocarbon is a broad general term that covers a wide range of compositions and colors, everything from black to pale yellow so you cannot rule them out because: "from what I have gotten from many of the comments is that hydrocarbon inclusions look dark not light." That statement is simply not true.

28th Nov 2015 13:24 UTCJacob Zonderman

Got it, thanks.

28th Nov 2015 14:40 UTCBob Harman

A few fun facts about the Illinois-Kentucky fluorite district.

Alan Goldstein covered this subject quite well including many great pix in his Min Rec article about 1996 or 1997. Ross Lillie, the Ozark-Mahoning company geologist had a great collection of specimens, saved for him by the miners. He sold them to several dealers about 2 or 3 years ago. In the 1970s and until about 10 years ago great specimens were easily obtainable for a small fraction of today's prices. If you were to go down to Cave-In-Rock, Illinois from the 1960s until about 1998 virtually every shop had collectible specimens for sale. The town is small, but very scenic along the Ohio River. The fluorite processing plant is in the neighboring town of Rosiclaire. I had heard that green Colorado fluorite was shipped in for processing and I have found some green examples there along with the local stuff. As of about 2003 the only head frame still standing was the Annabel Lee in the Harris Creek mining district. This could easily be seen when the trees were bare; it is just West of Illinois rte 1 north of Cave-In-Rock. As of 2003 lots of multicolored chips could be found at multiple sites and the bushy edges of the old mining parking lots etc. These make for good faceting material and I have had several 30ct to 50ct colored stones faceted from the chips. If you collect down there and crack large boulders, the smell of oil is very strong. There is a lot of oil, both oily and hardened as still part of the rock.

The Hastie Quarry was still active as of several years ago. The Hastie brothers still own the mining rights to some of the local land. As I remember it (and I may be wrong), the quarry is north of Cave-In-Rock on Illinois rte 1. It goes into Spar Mountain and is a crushed stone quarry with no fluorite (?) production. Blasting into the side of the hill occasionally intersects with old mining adits from the local Harris Creek district mines. There used to be collecting trips into the quarry, but a collector left a crack hammer there and it fouled up their equipment so the management cracked down on club collecting. As of before 2000 no collecting was allowed. Nowadays?????? Both on the Illinois side and Kentucky side there is still a lot of ore in the ground: fluorite, galena for lead, and sphalerite for zinc and some barite; several years ago there was some talk of reopening some areas, especially on the Kentucky side, but now that commodity prices are so low, I doubt that there is anything going on down there. But I am just not sure of the current situation. If you go, make sure to see the Ben Clement museum in Marion Kentucky; lots of great specimens from Mr. Clement's collection. I believe that town has a collecting weekend so find out about that as they gain entrance into several Kentucky side mining sites.

CHEERS.....BOB

29th Nov 2015 17:06 UTCDavid Von Bargen Manager

The Clement Museum still sponsors some summer time collecting opportunities.

http://www.clementmineralmuseum.org/digs.html

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