Monday, February 19, 2024



55 or so dealers spread out at the Miners Coop Show

One of the many Tucson shows that I make time to attend is the Miners Coop Rock Show. This venue seems to be the most western and most northern show situated at Mike Jacobs Sports Park at the corner of Ina Road and I-10. The location is away from the hustle and bustle of the major venues in and near the city center, southeast near the Kino and Holiday Inn Shows, along the Oracle road and I-10 motel strips and the 22nd street monster. The Coop show is a mom & pop, old timey show where vendors are outside or small open tents displaying thjeir wares.  Don’t worry about a rainstorm, of which are numerous, just throw a tarp over the specimen tables and retreat to their small RVs parked behind the tables. The show is described as the people who dig and mine and the home of the diggers and do-ers. 


All sorts of rocks, minerals, and fossils for sale.

Not all minerals are what they appear to be! m This is a sack of nice fresh oak acorns.

The vendors are likely to be perched on a lawn chair and snoozing in the sun but are more than willing to engage in a lively conversation. These are the vendors who may have come from a month in Quartzite and may be heading to February/March New Mexico shows in Los Cruces, then Deming,  Albuquerque, Santa Fe, and Truth or Consequences—any place to avoid snow shoveling back at their home base. 

Kim and Bodie from Runnin Boar Minerals sell a variety minerals including amazonite from their quarry.

Generally speaking the vendors are about the same each year and I enjoy talking to a parrot from Arkansas, the azurite blueberry dealer from Moab, and Kim and Bodie from Divide, Colorado, just up the road from my home base in Colorado Springs. No expensive motel rooms or giant tents or the convention center –just a bunch of friendly diggers and do-ers! 

What I found at the show was small box, still partially damp from a rain, that had been tossed in a flat of minerals with other specimens. Always curious, I pulled out my loupe to take a peak at the specimen labeled “ montgomeryite, Tip Top Mine, Black Hills”.  Wow. I zealously guarded the box and continued to peak at others but none piqued my interest. “How much do you want for this mineral? How about three bucks.” I hesitated but pulled out the money and was happily on my way. I had previously blogged about the mineral a couple of times. However, montgomeryite is a pretty rare secondary phosphate named for Arthur Montgomery and is associated with Colorado Springs, the Black Hills, and Utah—three of my favorite places.

In 1940 E.S. Larsen of Harvard University described two new minerals collected from phosphate nodules near Fairfield, Utah.  Larsen had been working and describing minerals from this area for at least a decade and finally “got around” to formally naming the hydrated calcium magnesium aluminum phosphates: overite [CaMgAl(PO4)2(OH)-4H2O], named for Edwin Over of Colorado Springs, and montgomeryite [Ca4MgAl4(PO4)6(OH)4-12H2O] for Arthur Montgomery of New York City.

Over and Montgomery had spent part of the years 1936-1940 prospecting and mining phosphate nodules from Clay Canyon near Fairfield in the Oquirrh Mountains southwest of Salt Lake City. They were mainly after variscite, a beautiful green, hydrated aluminum phosphate [AlPO4-H2O] that was sliced for mineral collectors and cabbed for jewelry. However, these nodules also contained a plethora of micro minerals that were of great interest to collectors. Today the Fairfield site is closed and remediated or perhaps open to the claim owner every few years?

Today, the best-known montgomeryite crystals are found from a few mines in the Black Hills of South Dakota, especially the Tip Top Mine near Custer, formally a lithium mine in pegmatites associated with the Precambrian Harney Peak Granite.  Here montgomeryite generally occurs as small lath-like crystals that are flattened, striated, elongated and capped by a pyramid.   Crystals are translucent, have a vitreous luster, and a hardness of ~4.0 (Mohs).  At the type locality at the Little Green Monster Mine in Utah the crystals are generally colorless to pale green and occur in nodules that are of sedimentary origin.  At the Tip Top Mine the lath-like crystals are colorless to some sort of a red to orange to salmon to pale yellow color and are associated with several other secondary phosphate minerals and primary phosphates like triphylite as well as and the pegmatitic microcline feldspar.

Montgomery laths on a microcline matrix. Black mineral is some sort of a phosphate perhaps rockbridgeite and/or triphylite. Width FOV ~ 7 mm.

I felt fortunate to locate the specimen, especially with the low price, and will continue to seek other Tip Top and Fairfield specimens such as the millisite found at 22nd Street show described in the February 6 post. 



Saturday, February 10, 2024



 Aerial view of the Kino venue. Photo courtesy of

My next venue on the schedule was the Kino Gem and Mineral Show situated south and east of downtown along I-10 heading east and on Ajo Way. It is among the most isolated of the venues but is quite large with ~225 vendors. Kino is a show where one goes to get exercise by walking and walking and walking. Most vendors are situated in tents open to the weather although there are a couple of the really giant tents. Kino is the place to go if interested in “large” quartz crystals and “big” rocks and large water fountains. If one is buying at Kino there is a possibility of the need for a flatbed truck and loader to carry home your loot. There are also numerous jewelry booths in the big tent where one can purchase lesser priced rings, pendants, bracelets, etc.  And of course, carved skulls and beads are plentiful. What generally was missing are mineral collectables for you home cabinet. But, if you are interested in doodads, rugs, magic minerals, handicrafts, trinkets, etc. this is your place. And, the parking is plentiful and free. Lookers could easily spend a day here and if interested, pet a goat. 

Mookaite (locally coined) is a silicified sedimentary rock, actually a colorful indurated radiolarite only known/collected from the Lower Cretaceous Windalia Radiolarite (a geological formation) in the Carnarvon Basin of Western Australia. The rock is composed of gazillions of microscopic radiolarians that have a siliceous, usually opaline, test (their “shell”). This particular radiolarite forms in the weathering profile of the Windalia. Every year I come to ogle at these colorful slabs.


Sometimes you just toss all of your extra rocks on a table and see what will sell for a dollar.

And so, the walk begins at the south end near the parking lot. Not certain that I can see the north end of the aisle!!

I guess this is a brecciated conglomerate of some sort. Definitely a yard rock that will not fit in the trunk of your passenger car.

Another one you need the truck for—a large quartz turned into a yard fountain.

I don’t know if the goat (look closely eating hay) comes with the geode. But it was friendly, and kids (and some adults) loved to oh and ah and pet it.

This is a mighty big concretion, about four feet tall. Bring the loader and the truck.

This building is mostly filled with amethyst concretions.

Shell of a giant clam, perhaps Tridacna sp. Today most giant clam species are overexploited due to extensive harvesting for food ornamental objects.

After hunting around for “something” to take home from the Kino Show, I finally found an answer in a lonely looking perky box mixed in with some larger specimens: a quartz base topped with a porous and gnarly looking mottramite, a lead copper vanadate [PbCu(VO4)(OH)], and then within a mottramite vug, shiny gold. Wow, who could turn down a specimen of gold? Not me!

The mounted specimen came from the Shelby Mine, Gold Basin District, White Hills, Mohave County, Arizona. The Gold Basin District has a long history as an 1881 publication (see MinDat) noted mining started in the 1870’s but remoteness from the base of supplies retarded developments of the half dozen mines. Jump ahead to the present and noted the District has~ 533 active claims and 19 producing mines. In addition, Gold Basin Resources Corporation has leased/is leasing ~40 km2 in an active project to “mine” gold from   shallow depths (surface to ~100 m or so).  And, the project is easily accessible by major highways. Things have changed in the last 140 years).

Quartz matrix, dark mottramite, and the shiny gold in a vug. Width FOV ~5 mm.

The bedrock is composed of Precambrian and Cretaceous granite and gneiss. The richest mineralization seems to be stacked along major fault zones. Thus far, the gold is oxidized and lacks sulfides and is prime for heap leeching extraction. They are looking for investors!!!

And I close with something I tried to reinforce in my students: Your mind is like a gold mine, if you dig deep, you will find something golden        author unknown.