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GeneralFranklin picking table historical mythology

19th Sep 2014 17:58 UTCHoward Heitner

The description of the Franklin NJ picking table in the Mindat glossary is historically inaccurate, at least for the 1920's The picking table was illuminated by visible light.

1. Palache (1935) says "several men" removed "waste" . No mention of ultraviolet lights. Could a few men sort all the ore coming out of the Palmer shaft?

2. The only source of UV in those days was the very weak " iron spark gap". A mineral had to be a few inches away from it to see anything.

3. Palache states that non-fluorescent minerals such as barysilite were first found at the picking table. This mineral was found in such small quantities that it was hard to get a sample big enough for chemical analysis. If the picking table was in the dark, how could such a minor non-fluorescent mineral be noticed?

4. A picture of the picking table published in several sources shows a linear belt. Palache describes the picking table at the Palmer shaft as circular.

In my opinion this is what actually went on.

Unusual or different looking minerals were taken off the picking table and taken to a dark area to be examined under the iron spark gap. They were also sent for chemical analysis. This is how new fluorescent and non-fluorescent minerals were discovered at the picking table. The men mentioned by Palache were probably just pulling out junk like pieces of wood, old drill bits etc.

19th Sep 2014 18:13 UTCHoward Heitner

This picture supposedly from Franklin, NJ is actually from the Cannon coal mine in Franklin, Washington

19th Sep 2014 20:15 UTCMark Heintzelman 🌟 Expert

Howard,

I can't speak specifically to what was used at Franklin (maybe Chet knows for sure), but Mercury vapor lamps were invented in 1901 by Peter Cooper Hewitt, and his improved 1903 version found widespread industrial use. The ultraviolet light from mercury vapor lamps was already being applied to water treatment by 1910.

Given the lack of fluorescence in the other ore minerals, both Zincite and Franklinite, it seems logical that they wouldn't want to filter out a significant amount of visible light, but given the highly fluorescent qualities of willemite, they probably wouldn't need to in order for these lamps to still serve a useful purpose for separation. Keep in mind, ALL short wave and most medium wave UV light is blocked by earths atmosphere, and is not a component of normal sunlight as we experience it These lamps provided the full UV wavelength spectrum and could have been employed for such purposes within that time frame.

As for the "waste", it should be obvious that they mean gaunge, or non-ore rock. A few component species of this waste rock are even spelled out on that page. All mines needed to separate ore from waste rock in some manner, usually employing a picking table or belt.

The significance of "the Picking Table" at Frankiln is that many species were first found and identified from specimens off this table, meaning that they could not be assigned to any more specific area within the ore body other than "Franklin" (barring any rare or notable associations that might help to suggest one).

MRH

19th Sep 2014 21:34 UTCHoward Heitner

I repeat one of my questions. How many men would it take to sort out all the non-willemite pieces from the tons of ore coming out of the Palmer shaft? To my mind “several” means three or four. They must have worked very fast.

The early industrial mercury arc lamps were made of ordinary glass which does not transmit SW. A lot of willemite responds weakly to LW. In addition the visible light from the lamps would have made the willemite very difficult to see.

Palache only describes the fluorescence of Franklin minerals under the iron spark gap. Why did he not use the lamps at the picking table or buy a mercury vapor lamp for his own use?

Remember, I am only talking about the 1920’s. Around 1935 Tom Warren commercialized a usable SW lamp with a silica tube and a filter to take out some of the visible light. It is possible that after this type of lamp was on the market, that it was used in some way at the picking table. I am still investigating this.

19th Sep 2014 22:13 UTCAlfredo Petrov Manager

Howard, I wouldn't call the iron spark gap "very weak". It didn't need to be just "inches" away from the samples to work. There is a story (Sterling Gleason (1960) Ultraviolet Guide to Minerals. p 213-215) about George F. Kunz in 1903 pushing iron spark gaps on wheels down the aisles of the AMNH in New York to observe fluorescence of specimens in the cases. If Gleason's story is true, then the iron spark gap was strong enough to elicit a fluorescence response from a distance, without filters, despite the flood of visible light that was also generated! One wonders about the health of Kunz's eyesight afterwards :-S

Given the proximity of Franklin to the AMNH, it would not surprise me if mine management were already aware of the fluorescence of their ores by the end of 1903.

19th Sep 2014 22:42 UTCHoward Heitner

Gleason describes the spark gap that Kunz used as "giant " producing '"white sheets of flame" The glass of the display cases filtered out the SW, so they saw fluorescence in autunite and a few other minerals.. Palache probably used a much smaller unit like the one produced by General Electric about 1917. It gave a mixture of SW, LW and visible. It is shown below..

20th Sep 2014 01:26 UTCGary Moldovany

I have seen a photo of the picking table at Franklin, it was circular. Here are two more bits of information: The miners who worked at the picking table were either disabled or had some physical condition that kept them from working in the mine. The miners who worked the picking table had the finest collection of Franklin minerals, several of them were well known. I believe that Mark was right about the "waste removal" since the ore separators at Palmerton removed most of the unwanted minerals during processing. I have also heard that the lead-based minerals, for example esperite, were removed at the picking table. I always understood that the iron arc lamp was mounted above the picking table and that it was quite large.

20th Sep 2014 03:51 UTCHoward Heitner

Again my evidence from Charles Palache is in negative form. In 1928 he publishes

THE PHOSPHORESCENCE AND FLUORESCENCE OF FRANKLIN MINERALS

CHARLES PALACHE

The use of ultraviolet light as yielded by the iron-arc spark-gap to determine the presence of willemite in mill-tailings has long been an important practice at Franklin. From it has grown up the constant use of this apparatus in determining the presence in the Franklin ores not only of willemite but also of a number of other minerals which give characteristic reactions to this form of stimulus. Since these reactions may not be generally known it seemed desirable to give a brief account of the apparatus used and of the observations which may be made with it.

No mention of ore sorting or use of the spark gap at the picking table to remove lead minerals.

20th Sep 2014 04:49 UTCAlfredo Petrov Manager

Some questions (to which I do not know the answers): Charles Palache was a mineralogy or geology professor, not a mine or mill engineer. How much did he understand, and how much attention did he pay, to the industrial side of ore beneficiation? What do we know about how detailed was Palache's familiarity with Franklin? Did he ever do extended research there? Did he visit it often or only once? On a typical working day, or on a holiday? Or did he base his writings just on stuff he was told by others? What other contemporary sources do we have, other than Palache?

20th Sep 2014 11:42 UTCHoward Heitner

One person who was at Franklin almost every day was Lawson H. Bauer, the chief chemist, who analyzed the new minerals.. He wrote two articles with Palache about larsenite and calcium larsenite (esperite) In the opening paragraph of each article it is stated that these minerals were first found on the picking table. There is no mention of fluorescence or ultraviolet lighting of any kind.

20th Sep 2014 12:32 UTCHoward Heitner

In a much later article (1981) R. W. Jones reported that in the 1940's people were doing some self collecting in the mill with hand held lights (probably portable Mineralights) This is probably how some of the mill workers obtained their great collections of Franklin fluorescents. The text is shown below.

The luminescence of many Frankl in

species explains the strange behavior

noted among miners and mineral

collectors over the years. It is reliably

reported. for instance, that in the 1940s, as

miners watched the broken ore coming

into the mill, it was not unusual for one of

them to grab a chunk and dash off to the

nearest dark telephone booth where

fluorescent response might be evoked

with a hand-held lamp.

20th Sep 2014 13:05 UTCDavid Von Bargen Manager

"A large number of the mineral species found in Franklin fluoresce in ultraviolet light. The New Jersey Zinc Co. has placed an electric arc producing ultraviolet light in a darkened inclosure near the picking table for the convenience of workmen."

Guidebook: Eastern New York and western New England

Publisher U.S. Government Printing Office, 1933

20th Sep 2014 14:31 UTCEd Clopton 🌟 Expert

A photo of the circular picking table at Franklin, circa 1945, appears in Mineralogical Record 22(6):466 (November-December 1991) in Lawrence Conklin's off-and-on column "Mineral Stories". It illustrates a story contributed by Walter Pickut of Wellsville, New York entitled "A Franklin Saga" describing how Walt acquired from Ewald Gerstmann what was supposedly the very last piece of ore to land on the picking table when the operation was shut down.

20th Sep 2014 14:33 UTCHoward Heitner

The fact that the New Jersey Zinc Co. put an iron spark gap near the picking table is consistent with what I said initially. Interesting pieces of ore were taken off the picking table and examined under the iron spark gap in a darkened area. The whole picking table was not illuminated by the iron spark gap or any other UV source for the purpose of sorting out gangue or undesirable minerals. If a workman found a piece of esperite it was probably taken home to go in someones collection or to be sold. If it was pulled off the picking table by someone like Lawson Bauer it was taken to the lab and studied. Remember also that non-fluorescent minerals were also first found at the picking table.

The ore was first crushed and ground. The franklinite was then removed by powerful magnets. Then the willemite was separated by density, from the gangue. The machines used to do this were called Wilfley tables. The iron spark gap was used to monitor this process. That is to say,, to determine if any willemite was being lost in the tailings. Perhaps this is how the "historical concept" that the spark gap was used to illuminate the "tables" used for ore beneficiation originated.

The men at the picking table pulled out wood and pieces of iron that would jam the crusher or cause problems in the grinding.

20th Sep 2014 14:58 UTCHoward Heitner

My old Min Recs. are packed away in my attic. Does the article in Min, Rec. which shows the picking table say anything about UV, fluorescence,, ore sorting or any of the other things being discussed here

20th Sep 2014 17:34 UTCAlfredo Petrov Manager

I suppose one argument in favor of there not having been a large iron spark gap over the picking table is that we don't have reports of workers going blind or getting skin cancer after a few years of working there.

20th Sep 2014 23:02 UTCHoward Heitner

Thank you to E. L. Clopton for pointing out a valuable reference. . The picture in Mineralogical Record 22(6):466 (November-December 1991) supports my version of the picking table. The men are picking out out wood, iron and "low grade ore" Low grade ore probably means obvious chunks of plain rock like Franklin marble. No mention of fluorescence, UV lights, sorting out lead minerals etc.

21st Sep 2014 13:01 UTCReiner Mielke Expert

Hello Alfredo,

"There is a story (Sterling Gleason (1960) Ultraviolet Guide to Minerals. p 213-215) about George F. Kunz in 1903 pushing iron spark gaps on wheels down the aisles of the AMNH in New York to observe fluorescence of specimens in the cases." The cases in those days where at a very low angle and glass covered so I doubt it would have worked at a distance. It is more likely it was on wheels because of the weight and specimens were carried to it for close examination.

22nd Sep 2014 04:03 UTCHoward Heitner

Another item appears to conflict with the Mindat glossary.that is to say that the picking table was used to remove fluorescent lead minerals. Lead was a problem in the zinc industry. Here is what Palache had to say about lead.and arsenic

"Another element of economic importance in the mineralogy of the ore deposits is the presence of minute amounts of compounds of lead and arsenic, as even a trace of lead in the concentrate is objectionable. Besides its sparse occurrence as native lead and in galena, lead is found in the very rare silicates mar- garosanite, barysilite, nasonite, calcium larsenite, larsenite, and roeblingite and in the arsenate hedy- phane. Of more importance is its persistent presence in hardystonite, as that mineral is much less rare than the true lead compounds. The arsenic com pounds, though rather numerous, are rare and local. They include the arsenides chloanthite, lollingite, and niccolite; the arsenates allactite, arseniosiderite, cahn- ite, chlorophoenicite, hedyphane, holdenite, and sva- bite; and the arseniosilicates schallerite and ferro- schallerite and some of the friedelite. All the minerals listed in the preceding paragraph are removed from the crude ore wherever possible, both in the mine and on the picking table. Their total amount in the ore as mined is inconsiderable, and such are the pains taken to check the lead con tent of the concentrate before smelting that the zinc manufactured from the ore is practically lead free".

There is no mention of fluorescence as a screening method. Both fluorescent and non-fluorescent minerals are being avoided. The major portion of the lead in the ore appeared to be contained in the hardystonite, which according to Jenkins And Bauer contained only from 0.66 to 3.55 % lead oxide, It was much more abundant than the lead minerals like esperite etc. Its fluorescent response was reported as;

“Under the iron-arc spark gap it fluoresces a dull, faint violet or not at all”

22nd Sep 2014 12:43 UTCHoward Heitner

Here is a description of the picking table written in 1917 in "National Painters Magazine"

This ore passes through a revolving washer and is de livered on a circular, revolving "picking table." "Sort ers," seated within and without this table, remove the barren rock as it passes them, and dump it into chutes, from which it is delivered back into the mine as filling. The mud, etc., removed in the washer contains zinc and, after drying, is added to the ore at a later stage. From the picking table the ore is delivered to the crush ers, and from them it is conveyed by belts to rolls which

22nd Sep 2014 15:00 UTCHarold Moritz 🌟 Expert

Page 142 of Pete Dunn's 1995 work "Franklin and Sterling Hill, New Jersey: the world's most magnificent mineral deposits" briefly describes the Franklin picking table and shows a photo (Fig 3-18). Dunn describes it as "a 30-foot diameter, revolving, annular conveyor...staffed by men who had been disabled...to remove waste rock, timbers, tramp steel, tools, and Pb-bearing minerals such as hardystonite and hedyphane..." The pickers were experienced in spotting these minerals, but he makes no mention of the use of UV light. Dunn does not give a date, but presumably this was in the latter days of Franklin operation as he mentions there "had been an earlier picking table at the Parker Mill, and there was one at the Sterling Hill operations until 1957..."

The photo shows and names 2 men and fits the text description, though it only shows part of the annular conveyor, and more men could be out of view. There appears to be no provision for UV light; a plain, incandescent bulb hangs over the conveyor and a large window is visible (probably one of several in the room), so the room would certainly not have been anywhere close to dark. To see the "waste" as described, a brightly lit room would seem an obvious necessity.

Another photo (Fig 3-22) shows a linear picking table (location uncertain) with many incandescent bulbs and a window also visible.

In both cases, perhaps there was another section of the "table" or place nearby where UV was used, but that would have been dark and not easy to photograph, and thus very unlikely to have been documented this way...

22nd Sep 2014 16:37 UTCHoward Heitner

Thanks for the reference The picture was obviously taken prior to 1954 when the Franklin mine closed. . It is consistent with what Palache said about trying to remove lead containing minerals. What was not documented in the picture were the mill workers with their hand held portable SW lights doing "field collecting" during their lunch break!

So this revisionist historian concludes that the picking table was a great place to find fluorescent minerals, even though the New Jersey Zinc Company was not thoughtful enough to install the right kind of lighting. Every mineral collector knows that you should always bring the right equipment with you.

22nd Sep 2014 16:55 UTCHarold Moritz 🌟 Expert

Dunn does go on to say that it was a great place to find all kinds of minerals. But from what I remember from reading in many places in general, that was because the "picked" minerals would be lying on the floor, or buckets, etc., already hi-graded from the ore. So invited visitors or other mine staff could simply examine the pickings for rarities, etc., then take them somewhere for UV inspection.

Another mineral "problem" was tephroite. Visually it could look just like willemite, but was of course, worthless, and it was difficult to pick out without UV light cuz it doesnt fluoresce. But there is no mention of its removal at the picking table. It was avoided, at least later on at Sterling Hill, by the use of UV lights in the mine.

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