FMF - Friends of Minerals Forum, discussion and message board

[Tobi]

Thank you so much, Philip, browsing this is a pleasure!

[Philippe Durand]

thank you for sharing this field report.
a dream for only money pick collectors

[Philip Simmons]

Wow! It's been a whole year since I last posted any New Mexico adventures. Time really does fly. Much has happened in the past year, and I have had the pleasure of finding some good specimens. However, I will start off with collecting adventures from the past, including some of my most exciting finds in over 30 years of field collecting.

I am going to talk about collecting in the Carlsbad Potash District in the SE corner of New Mexico.

[Philip Simmons]

All of the History, Production and Geology comes from the article I wrote for the Mineralogical Record in January/February 2013.

The Carlsbad Potash District was first located in 1925 about 35 kilometers east of Carlsbad when an oil/gas well intercepted beds of a soluble reddish mineral. Analysis was performed on the mineral, and it was discovered to be almost pure sylvite (potash). More exploratory drilling revealed the presence of extensive beds of potash, and by 1930 the first shaft was sunk (U.S. Potash Mine) to develop the ore bodies. A boundary known as the KPLA (Known Potash Lease Area) was set aside in 1934 specifically for mining the important commodity used in fertilizer. More mines were soon developed, and by the early 1940's, eight large mines were operating in the District. The Kerr McGee mine, where spectacular blue halite is found, was first opened in 1965.

Mining peaked in the 1960's when typical yearly production amounted to more than 23 million ore tons. The Carlsbad District was the world's leading producer of potash from the 1930's through the 1960's. Production slowed by the 1970's and huge mines in Canada and Russia were opened that dwarfed production from Carlsbad. However, companies still managed to mine the extensive ore bodies and production is still ongoing today. Two major mines are currently operating in the District. Overall, the Potash District has produced greater than 900 million tons of ore and driven more than 16,000 kilometers of tunnel.

[Philip Simmons]

I started working in the District as a mining engineering intern in the summer of 2007. My boss, the Chief Mine Engineer (Tom), had a few cleavage fragments of dark blue halite in his office from the underground workings which piqued my interest. I had not really expected to do much collecting in the mines because of the evaporitic nature of the deposits, and seeing beautiful halite was quite the surprise, even if it wasn't complete crystals. I eventually convinced Tom to take me to the area that produced the wonderfully colored halite, and the resulting trip was one of the most memorable experiences of my life.

When I graduated from college in 2008, I was offered a position by the mining company as a planning and ore control engineer, and I accepted the position without hesitation. The mining company was fine with me collecting on my own time, and I spent many weekends exploring the blue halite zone, and came up with many great specimens and memories. Unfortunately collecting was halted in 2014 as the area became inaccessible through the ever present converging ceiling (known as the "back" in mining terms). The mines are relatively deep (500 meters) and all openings are slowly squeezing shut due to the soft nature of the rock.

[Pierre Joubert]

Thank you Philip. Fascinating stuff!

[Philip Simmons]

Now that I'm back from a great trip to Dallas to give a presentation and visit with many friends, I will continue to post about the Carlsbad Potash District.

[Chris Rayburn]

Philip, you may be coming to this, but what is the current thinking on the source of the color in these specimens? The explanation I've heard most often is radiation from trace isotopes in the halite, but I also understood that this was not yet definitive, at least as of several years ago.

[Philip Simmons]

Chris, I'm glad you asked! Tonight I am planning on posting pictures of the crystals we found, and then I will cover the topic of coloration in the halite. It is a very fascinating process, and we now understand in greater detail what causes the color compared to even a few years ago.

[Chris Rayburn]

Always happy to tee 'em up...and I'm not even a golfer.

[Philip Simmons]

We spent about 5 years (2007-2011) collecting the areas with the large cleaves until those areas became inaccessible due to mine convergence. With these areas no longer available, we had to find somewhere else to collect.

Several exploration trips in mid 2011 led to another location that had potential about 400-500 meters away in another stoped out area (Area 2). This stope (or "panel" as it is called in a room and pillar mine) had once been mined to over 2 meters in height, but after 30 years of convergence, had been reduced to less than 1 meter tall in many places. It did not have the large cleaved crystals, but a few smaller ones were evident in the ribs (walls) of the drifts. Most of the crystals had been cut in half by the previous mining, but smaller crystals meant better chances of surviving without being damaged. A couple of more trips were required to find a good area to collect, but when we did, the experience was a field collectors dream.

On the far side of the panel, the miners had cut through two pure sylvite seams ranging from a few centimeters to about a meter thick which contained numerous halite crystals encased in the sylvite. In what was to become known as the "Blue Ice" and Frozen Blue" seams, large sections of the ribs (walls) had spalled off of the main rock and had fallen down in the drifts. After crawling through a 40 cm pinch point during the discovery trip, I began to notice dark blue cubes frozen in the ribs and the fallen segments of the spalled rock. The second thing I noticed was that there were blue crystals lying all over the ground! The first few trips to these two seams we barely had to use collecting tools at all: all we had to do was walk (or in many cases crawl) along the drifts and pick loose specimens off of the floor and wrap them up for safekeeping. I'm sure collectors have often heard or dreamed of finding a locality for the first time where specimens were just lying everywhere waiting to be collected. This discovery was a realization of that dream!

Not only were the specimens plentiful at first, but the quality of the crystals were many orders of magnitude better than anything found previously. Many of the cubes less than an inch had survived the convergence pressures, and were associated with a nice contrast of white or colorless sylvite. In exceptional cases, crystals as large as 25 cm were collected without damage. Even after the easy material had been collected, most of our collecting time was spent crawling along the drifts and breaking apart the spalls to find the crystals inside. In my 30+ years of field collecting, this was my most exciting, memorable and productive adventures ever. The panel continued to produce exceptional specimens until 2014 when the whole blue halite area became inaccessible with mine convergence. Unfortunately, no specimens will ever be collected here again, but I feel blessed to have had the opportunity to collect so many great specimens while the chance was still present.

[Philip Simmons]

I will start with early photos and progress to the later specimens after the Blue Ice and Frozen Blue seams were discovered.

[Philip Simmons]

Now for some photos of many of the great specimens we found.

[Philip Simmons]

Not only were we able to collect blue halite, we also found a good number of other types of halite along with some rare evaporite minerals at the Kerr McGee mine.

[KJ Seraph]

Very beautiful! Are you going to keep it for display only?