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Collected With Your Dirty Hands
Posted by Matt Courville
Bob Harman July 12, 2018 09:58PMJON, As I have previously noted......really interesting and nice finds and with potential nice rewards.
Like DAVID K J, I also have a question. Most of your postings show slabbed examples. How are these being found? Are they from differing dump sites and then slabbed, slabbed from the same or adjacent boulders, or nearby areas in the mine itself or ????? CHEERS......BOB
Alfredo Petrov July 12, 2018 10:21PM"High grade" ore is wonderful stuff for mineral collectors and museums, but of little interest to modern mining companies because of the fact already mentioned, the typically small size of the orebodies. And add to that the problems like irregular distribution, complex chemistry, safety issues of working where there is already a rabbit warren of poorly mapped underground diggings, etc.
Jon Aurich July 12, 2018 10:35PMAlfredo, High Grade Ore is great for me. I don’t understand why people bring up commercial value of the mine, I’m not here to sell it or try to promote it, only as a Mine of historic value. Although, I’m sure that a Mining Company would love to uncover another small mine like the Florence, one that produced over 650 million dollars in today’s prices !! Not a bad haul for a small Mine........
David K. Joyce July 12, 2018 10:36PMAlfredo,
ANY mining company LOVES high grade if there is enough of it to mine profitably. They will find a way to mine it safely and efficiently. I have had many prospectors come to me (in my old mining role), wild-eyed with a piece of high grade. I just ask them how many tons of it are there? What is the potential for tonnage? There are many veins that have a glob of gold here or there that, as grab samples, are "high grade". When the same sample taken in context of the entire vein or veins, the average grade is often low grade or no-grade. Many mining companies have undertaken drill programs on the basis of high grade gold samples only to find out that there are not enough tons to mine profitably. The gold is there, just not profitable enough quantity to undetake the permitting, environmental analyses, bulk analyses, engineering, financing and legal costs. There are more factors but you get the idea.
Goldcorp found one of the highest grade orebodies ever found 20 or so years ago. Many millions of troy ounces in a relatively small volume of an orebody. They started mining at average head grades of 2.5 oz/tonne or so. Locally, the ore ran a thousand ounces Au per ton. That high grade orebody resulted in the grounding for one of the largest gold mining companies in the world.
Don't get me wrong! I love high grade gold and silver samples, especially from historic mining camps. They are usually relics though and not representative of value of the deposits today.
David K. Joyce
Best, David K Joyce
Jon Aurich July 12, 2018 10:46PMMr. Harman, the ore is slabbed to show maximum features of the ore. These specimens are found in different areas of many piles. The complex distribution of the Gold and Sulphides is interesting to me, Gold can be found in the Famatinite alone or just with the Quartz, it can be just associated with the Bismuthinite, It could Just be in combination with Goldfieldite. It could be in one Sulphide or all of them together. The ore is in many different associations, and that is only the Florence Property, there are many more different associations of the ores in the other rich mines of this district.
Jon Aurich July 12, 2018 10:54PMGoldfield was a great mining district. It may still hold the record for the highest average of Gold production, 7.5 million tons of ore with an average value over one half ounce per ton. 97% of that value came from an area of less than 200 acres in size. This Epithermal deposit had an overall maximum depth of 500 feet.
Alfredo Petrov July 12, 2018 11:28PMYes, David, I'm sure Sumitomo is happy to have the Hishikari deposit, and I'm sure any mining company would indeed love a giant high-grade deposit, but how often do they find one? Most of the time their accountants would rather they worked a more large-scale low-grade deposit with a predictable cash flow than a small irregular deposit. And it's very lucky for we collectors that the big corporations don't take much interest in the small high-grade deposits, otherwise all our nice specimens would've been crushed before we could get our hands on them. I'm in no way disparaging the specimens, just thankful that no big mining corporation would be interested in them.
David K. Joyce July 12, 2018 11:37PMAlfredo,
By my figuring, there seemed to be one larger, high grade Au deposit found about every 10 years or so SOMEwhere. Goldstrike, Red Lake, Fruta del Norte. Anyway, mining companies explore and whatever they find, they find. If it is not a big enough deposit for the bigger companies, they sell it off to the mid-tier or smaller mining companies. It is tough to make a mine happen these days no matter what size of deposit or company!
David K Joyce
Paul Brandes July 13, 2018 12:36AMI will have to introduce my wife to this thread, who is an avid Goldfield historian and wrote the description for the Goldfield page here on Mindat (https://www.mindat.org/loc-3894.html).
I wonder if there shouldn't be a new, separate thread solely on Goldfield since so many folks seem to be interested in this fascinating place...
David K. Joyce July 13, 2018 12:42AMGoldfields was a real mining camp with "jewelry stopes" by the sounds of it. On average though it is not what I would call a "high grade" operation, other than the high grade zones. To operate an underground mine you need a few million tons of 0.35-0.45 oz/ton to be modestly profitable, these days. We used to say 0.5 oz/ton was a good grade for an underground mining operation. The "high grade" underground mines that Alfredo and I have been speaking have an average grade measured in ounces per ton. Red Lake was 2.5 oz/ton in the first decade or so. The Hishikari underground mine is about 1.3 oz per ton and has been running at that for many years. Goldfields averaged 0.6 troy ounces per ton. That is "good" average grade ore. No doubt there were high grade pockets/stopes/zones in it. Most mines have those. Open pit mines are a different story and can be profitable at 1-2gm per ton (0.06 oz per ton!) with very high tonnages and economy of scale (60-100,000tons per day operation). There are lots of variables.
Bottom line is, Jon, that the Goldfields district sounds like a good grade mining area with some nice, really high grade zones. Either that or, if 7.5 million tons were mined, I'm missing something.
Keep finding that high grade!
David K. Joyce
Jon Aurich July 13, 2018 01:17AM7.5 million tons = 5.4 Billion, nothing to miss there ...... also, The Goldfield Consolidated Mines Company stated that over one million dollars alone was stolen (High Graded) at the Mohawk Mine in 1907, and 1.5 million was estimated stolen at the Florence, Red Top, Jumbo and January Mines, that would total at around 125,000 ounces that were stolen, with a value of today at about 170 million dollars !!!!! A lot of Gold...
Jon Aurich July 13, 2018 02:18AMGoldfield Nevada. Another great find. A High Grade Gold Specimen from the famous Rustler #2 and Florence Mines. This specimens association with Sulphides and Native Gold are different from the last specimens that were posted. Fantastic ore. 1” x 1” x 1/4”.....
Jon Aurich July 14, 2018 11:41PMHello Matt, I can post photos of the mines and the colors of the waste piles on where some of the specimens are coming from. Backfills from underground are another area. I have to limit exact locations of certain piles as people will tend to Trespass without asking permission to enter and dig holes in the piles. I myself, do not even dig the piles, only surface harvesting, as I want to keep the dumps in original condition.....
Keith Wood July 15, 2018 01:45AMDavid,
Underground mining is getting head grades down to as low as 0.15 ounce per ton range these days using modern mining methods and open stope methods. However, this is in bulk tonnage deposits like Carlin deposits. Vein mines generally still need higher grades.
The mines at Goldfield were very high grade, and the district produced about 4 million ounces. ANY company would be delighted to find such a deposit, as higher grades mean lower costs per ounce.
Jon Aurich July 15, 2018 06:28AMHi Keith, I was hoping that others like you would realize the wealth that was generated from this district. Over 4.5 million ounces were recovered , but even more was produced but stolen through High Grading, estimates range well over 125,000 ounces were stolen during the boom era. Others on this thread have said that the ore was hard to recover the Gold, the right Mill was built and its recovery was between 94% - 96%, a pretty high yield I think...
Jon Aurich July 17, 2018 03:24AM
Chris Rayburn July 17, 2018 01:46PMI took a rare summer trip to New Mexico last weekend (usually a winter destination for me) and collected at the Blanchard Mine in Socorro County. We chose an outcrop of silicified limestone just outside the main adits. After a half-hour of sledge and chisel work, I opened a crack and was able to lift a large slab off of the top of the outcrop. Underneath was a wide seam of fluorite and baryte with numerous vugs. Bingo! We recovered dozens of nice fluorite plates, baryte clusters and combos. Photos show:
IMG_1550: The fluorite/baryte seam, just after I uncovered it
IMG_1551: The underside of the slab that covered the seam
IMG_1553: Freshly dug fluorite and barite waiting to be wrapped. The large baryte on the lower left is roughly 15 cm long.
Matt Courville July 19, 2018 12:54PMGreat shots Chris! I love the context of collecting with the specimens. For all that is good with museums, you don't often get these real-life photos with the 99.9% of what can be actually collected at a locality. I should start a 'Collecting with your Injured Hands' thread with all of the collecting issues people experience for kicks - just got a bizzare spider bite out collecting that never hurt, but made a quarter-sized bruise with a bump at the centre on my forearm the next day....;)
Chris Rayburn July 19, 2018 01:14PMThanks Matt. As others have noted, it can be very hard to pause and take photos when you're in the middle of a good find. I don't always manage to, but it's fun to share with others when I do.
If you zoom in on the photo of the seam above, you'll see spider webs. Each of the vugs was thick with web...obviously there was an opening that allowed spiders in. It's black widow country, and I was half expecting to roust a nest of them, but the webs were all abandoned. Keeps you on your toes!
Jon Aurich July 19, 2018 07:50PM
Jon Aurich July 19, 2018 07:55PM
Jon Aurich July 19, 2018 08:00PM
Edited 1 time(s). Last edit at 07/19/2018 08:06PM by Jon Aurich.
Paul Brandes July 21, 2018 03:58AMGood stuff Chris!
It has been many years since I was at Blanchard, but I remember having an encounter with said Black Widow spider in one of those cracks. Had I not seen it when I did, I surely would have felt her bite! I'm currently in the Keweenaw for over 3 weeks so while collecting, I'll try to get some "action" shots to post...
Jon Aurich July 21, 2018 04:55AM
Jon Aurich July 23, 2018 08:17PM
Edited 1 time(s). Last edit at 07/23/2018 08:19PM by Jon Aurich.
Jon Aurich July 23, 2018 08:25PM
John Montgomery July 26, 2018 12:10AMA vug of bladed baryte crystals which appeared when I chiselled a large piece of massive baryte into smaller pieces in the field. Collected in May 2018 at a new locality on Mindat. The trenches are on private property.
”There was a production of barite (heavy spar) in 1921 by H.C. Bellew, 6 Saint Sacrament St., Montreal, Que. of approximately 200 tons, from a deposit which is located on lot 20, concession X, township of North Burgess, Lanark county. No shipments, however, were reported during 1921 or 1922.", Ontario Department of Mines annual report,1922.
The baryte was used in the production of paper.
John Montgomery July 26, 2018 09:45PMShort prismatic schorl crystals with good lustre and up to 1 cm. sit on a bed of milky quartzes , which in turn sit on a phlogopite crystal section that has pink calcite as its matrix.
Only the tip of one schorl crystal was visible when I collected this specimen. When I etched it with vinegar over the period over several days, the schorl cluster and the quartz appeared.
Dimensions: 8 cm x 6 cm x 4 cm
Largest Crystal Size: 4.5 cm
Personally collected with John Biczok and Doug Scott, May 2018
Matt Courville July 30, 2018 02:42PMGreat new finds Sean and John. Sean - with the particular lighting on the 1st photo, it looks like it could be from a horror movie trailer don't you think ;) ? something like 'Analcimes in the Basement' or 'The Shinnies' or 'The Extractorcist'
I'm also a fan of seeing people posting from lost and forgotten places - these spots have hope that they are not picked-out as well
Edited 1 time(s). Last edit at 07/30/2018 02:43PM by Matt Courville.
Andrew Debnam July 30, 2018 11:10PMnice finds Sean and John,
This is a high grade vein piece from Cobalt. It was attached to about a 250 lb boulder I metal detected under a jumble of spruce trees. My son and I managed to detach it from the boulder. The first photo shows the underside which was on the diabase rock and the second the outside rind which has been exposed to the elements for 100 years perhaps. It weighs 2 lbs 10 oz and is just under half an inch thick
Chris Rayburn July 31, 2018 12:52PMIndeed, nice finds everyone. I thoroughly enjoy following this thread.
Andrew, have you managed to identify any of the minerals in your vein specimen? I'm not that familiar with Cobalt area mineralogy.
Jerry, very interesting crystallization patterns in those mottramites. I've not seen this before.
Andrew Debnam July 31, 2018 01:41PMHi Chris, most of the pieces from Cobalt contain a mixture of silver, cobalt aresinides(sukkterudite for example ) and nickel arsenides (nickeline for example). Arsenopyrite is also very common. This piece is a high grade piece so it contains silver. Judging by the readings from my metal detector (fisher 75) it contains very roughly about 30-50 percent silver. The mixed metal mineralogy can be quite complex in Cobalt.
Bruce Cairncross July 31, 2018 02:43PMHi Matt,
As the "founder" of this thread, not sure if you're entertaining samples collected in the southern hemisphere? If so, here are two specimens I collected in July 2017 while visiting the defunct Berg Aukas mine in the Otavi Mountainland, Namibia.
This specimen (7.4 cm) is an intergrowth of dendritic descloizite and white dolomite crystals:
This one (8.5 cm) is a hand-specimen I picked up off the dumps and subsequently had cut and one side polished. It shows cores of red-orange vanadinite mixed with descloizite and partly rimmed by dark green-brown descloizite. The white matrix is mainly dolomite with some minor smithsonite:
Matt Courville July 31, 2018 05:00PMHi Bruce, as Wayne said - please post what you like. I'm sure everyone would just love to see recent Namibia field collecting photos if you have any. Post here or on the 'In-situ' thread if you feel like sharing/ have any of these.
Andrew - 'under a jumble of spruce trees' sounds like something I would do! hahaha The more uncomfortable and awkward, the better the finds it seems;)
Bruce Cairncross August 01, 2018 09:56AMI'm sure everyone would just love to see recent Namibia field collecting photos if you have any
OK, thanks. I'll see what I can "dig" up. We did a 2-week geological transect from Tsumeb in the north to Rosh Pinah mine in the south and collected some interesting specimens along the way...
Here's a shot of the Okoruso fluorite mine. This locality featured in a recent issue of the Mineralogical Record. I have some specimens self-collected in the old pit and these need to be photographed. I'll post them in this forum:
Scott Rider August 01, 2018 08:51PMChalcedony pseudomorph of calcite from jasper laden geodes. Saguache County, Colorado. July 28th find.
What makes the this one unique is the isolated rhomb, and its blue in color on white matrix. Most specimens that I have found are clusters, and many have the same color as the matrix. It has interesting rhombic features on the surface. There is another crystal next to it, about 3-4 mm, that has a different shape, a modified or maybe twinned rhome that creates a triangular shape with blue zoning as well.
Sorry for the lack of quality on the images. My regular camera is packed up for a move. The camera on my phone is mediocre at best...
Chris Rayburn August 02, 2018 12:34PMThat's a remarkably rich ore specimen Andrew. I don't have a metal detector but I once watched someone find a rich gold ore specimen on a mine dump near Central City here in Colorado. Looks like fun!
Scott, you've put my Saguache pseudos to shame yet again. Beautiful specimen.
Scott Rider August 02, 2018 02:08PMThanks Chris. I thought your finds were quite unique especially the larger cluster of dogtooth pseudos. It seems the calcite morphology differs quite a bit from just a short distance from each dig.
This is another example of how dirty some of the geodes get, when they are closer to the surface... I almost missed this specimen until I saw a tiny rhomb sticking out of the dirt.
With just a rinse, the dirt comes off easily. I didn't have high expectations until I rinsed it, and it revealed black pseudos. The colors I've seen in these pseudos go from colorless, blue, black, yellow, and pink.
Edited 1 time(s). Last edit at 08/02/2018 02:08PM by Scott Rider.
Rolf Luetcke August 02, 2018 11:44PM
Collected the piece this is on a few years back and I had an arrow on the other side for a different mineral. Turned it over and there was a small blue area and when I zoomed in I was surprised. The main mineral is chrysocolla with quartz and the little pieces I have no idea how this came to be like this. Just thought it was a fun little piece and I got this photo.
Andrew Debnam August 04, 2018 07:08PMlooks like a big feldspar Jeff, judging by the surrounding crystals. Here is another high grade vein piece from Cobalt just shy of 2lbs.
@ Chris, Cobalt is a fascinating place and well worth a visit anyone interested in early hard rock mining history or collecting not just silver but many other metals. Amazing to think veins like the little silver vein could be tapped at the surface in the Cobalt heyday
Guy Davis August 06, 2018 06:18PMI dug this loose columbite out of the dumps of the first prospect near the power line cut at the Case Beryl Prospects in Portland, Connecticut under permit in 2016. Most of the columbites found here are small and acicular, but this one exhibits classic columbite habit and has some of the irridescence often seen on the crystal faces. I was told this is a huge columbite for the locale and even the state. The best part of finding this was that it was buried in the dumps about a foot above an old beer can so obviously somebody missed it in their search for beryl.
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Copyright © mindat.org and the Hudson Institute of Mineralogy 1993-2018, except where stated. Mindat.org relies on the contributions of thousands of members and supporters.