By Bob Jones
Collecting minerals mined in Mexico after World War II was exciting as millions of collector specimens were mined and sold. During the war, Mexico’s mines produced the metals needed for the war effort. Imagine the wonderful specimens that went to the smelters at that time.
When the war ended, mines powered down, leaving countless miners jobless, miners who knew the underground workings and knew minerals without opportunity to use their skill. Surplus war materials like Jeeps were sold and military veterans, among others, combined the availability of four-wheel-drive vehicles with the opening of more federal lands and headed into the great outdoors, and the mineral collecting hobby grew rapidly. This rapid growth created a ready market for minerals, which prompted Mexican miners to go back to work, with some even forming mineral collecting consortiums.
POST-WAR EMERGENCE OF INDEPENDENT MINING
Instead of mining metal ores, the miners mined mineral specimens of every variety! Mineral dealers located close to the border became a ready market for access to minerals from Mexico. As miners realized they could make a living underground, the flow of minerals from Mexico’s mines became a flood by the early 1950s. The volume of minerals coming out of Mexico was so great some dealers became wholesale marketers operating in or near border towns like El Paso and Tucson. This market interest provided Mexican miners a ready outlet for their efforts and, in short time, dealers and collectors began driving to Mexican mining towns to buy directly from miners. As a collector, I certainly made the trip to buy several times.
It became so you could drop in on any roadside mineral shop across this country and buy nice minerals from Mexico.
Wholesale dealers like Tucson’s Susie Davis sold minerals by the flat and never lacked good stock. Miners catered to visitors but always kept the better specimens under the bed! We thought nothing of running into Mexico for a day or two on a buying trip. People who visited the Tucson Show by 1960, especially show dealers, planned ahead and drove to Mexico after the show to restock. In the decades before Bill Pancnzner published his excellent book, Minerals of Mexico, 1987, we thought nothing of heading into Mexico for days at a time to collect and buy.
During such a one-month-long trip, Bill and I, along with his son Chris and my son Evan, alternated camping, hotel stays, and even bedding down in guest cabins at a mine. Our goal was to acquire minerals for ourselves and the Arizona Sonora Desert Museum, where Bill was the Earth Science Curator and I served as a board member. These roles always gave us an advantage when visiting mines. Additionally, Bill could also gather information for his book. We always came home with fine specimens, photos, and good memories.
We planned to visit several mining areas during another trip, including Cerro de Mercado, Santa Eulalia, Mapimí, and Zacatecas. Unfortunately, I had to return home early and missed Mapimi, but we visited other areas, including underground collecting at Fresnillo and surface collecting at Cerro de Mercado and elsewhere.
Today, with the growth in illegal activities and a slowdown in mining, the halcyon days of rockhounding in Mexico are more past than the present. We can still go to Mexico to rockhound and buy through contacts like Benny Fenn and others who live there, but solo trips are less encouraged than in years past.
REFLECTING ON MEXICO’S MINING HEYDAY
When the Milpilllas mine in Sonora began producing some of the world’s finest azurite and malachite a couple of years ago, we headed there and were met at the border by our contacts where we convoyed to the mine area. We did business returning to the states while our contacts brought the specimens across the border.
In spite of some difficulties collecting in Mexico today, there are still plenty of fine Mexican minerals available, which is a testament to the huge quantity of specimens that poured forth in the last half of the 20th century. Miners are still working underground, and once in a while a big hit happens, like the find of legrandite that came out of Mapimí a few years back.
Among the most active mines during the heyday was Mina Ojuela, Mapimí, Durango. It is credited with producing some of the world’s finest examples of species like adamite, legrandite, and koettigite. It soon became the darling of Mexico’s mineral business 50 years ago, along with Santa Eulalia, Zacatecas, and San Luis Potosi. There are several mines around Mapimi, but Ojuela was the first in the Durango area. Over time, underground tunnels eventually interconnected the mines, so a miner might be digging in one mine but credit his find to Ojuela often to keep secret where he actually found the minerals.
Mina Ojuela was discovered in 1598 by Spaniards looking for riches. The ore vein they spotted was high on the wall of a limestone canyon, which created a problem. Reaching the ore was tough enough, but to actually mine the ore presented a major elevation challenge and an amazing feat of effort. In his book, Panczner offers a detailed description of the early Spanish efforts to mine Mapimi’s ores.
Mina Ojuela’s reputation as a specimen producer is due to the number of species it produced. The variety of species reads like the index of a mineral book. Until Mina Ojuela, adamite was a non-descript hydroxide zinc arsenate of modest color and crystal size. The type locality was Chañarcillo, Chile. The ancient silver at Lavrion, Greece, produced decent adamite as well, but it was not until the brilliant green crystal sprays of adamite from Mina Ojuela came out in huge quantities that adamite was a “must-have” mineral. Its crystals are in a fan-like shape or fat ball-like crystal clusters, single crystals and sprays all on a contrasting dark brown iron oxide matrix. The quantity found here was astounding.
I stopped by a dealer friend, Jack Amsbury, during a little show in Globe, Arizona, about 1979, and he had maybe 30 apple boxes full of choice specimens, so choice I had trouble deciding what to buy at his price, $2 per pound. Not long after that, I visited wholesale dealer Susie Davis, and she had racks full of boxes of choice adamite. Where is all that adamite now? I wish I knew.
Even today, adamite has a surprise or two for us. Another mineral found at Mapimí is olivenite, hydrate copper arsenate. The only difference between olivenite and adamite is the metal within; in one, it’s copper, and the other, zinc, which are compatible and can easily replace each other. Adamite is green thanks to a trace of copper in it. When copper replaces even more zinc, it is cuproadamite. Russian scientists went further in 2006 and found that if enough copper replaces zinc in some cuproadamite, it forms a new species, zincolivenite. Is your cuproadamite really zincolivenite? Ask Mother Nature!
The specimen-producing mines of Mexico are all known. The Spaniards started them out as silver mines, and some produced wonderful silver sulfosalt minerals like acanthite, polybasite, tetrahedrite, tennantite, and bournonite, all collector minerals. These same mines did not gain a reputation for producing native silver specimens except Batopilas mine, Sonora. The vast majority of the silver mines had the metal argentiferous galena, sulfosalts, and other collector minerals in the deposits. These old Spanish silver mines became major sources of fine collector minerals for decades in the 20th century as local miners became skilled mineral specimen miners.
The Batopilas mine, Chihuahua, produced fine native silver specimens in some quantity when opened in 1632 by the Spaniards, who found the local native people working it. Even today, this mine is known among collectors for its fine twisted wires and crystals of silver. Spaniards were only interested in mining the silver, so other minerals were bypassed, leaving them for collectors who followed!
MEXICO’S MINING EXCEPTIONS
Mexican native silver specimens have never been abundant, but Batopilas is the exception. Even in recent years, one miner got lucky and bought some nice native silver specimens — maybe 30 years ago — on his way to the Tucson Gem and Mineral Show. The specimens were in bad need of preparation and cleaning, as the silver wires were heavily encased in calcite. The dealer had to use acid on calcite to reveal more of the silver. Staying at a Tucson hotel where many dealers set up before the main show, the man bought bottles of swimming pool acid, which he put in his hotel bathtub to immerse his calcite-enclosed silver specimens. The calcite dissolved away, but the noxious fumes released by the reaction got into the motel air circulating system. The hotel had to be evacuated for a time. However, the silver sold well during the show.
Each of Mexico’s states is known for a particular mineral species. Sonora is famous among the lapidary crowd for agate. Among collectors, wulfenite from Sonora and nearby Chihuahua is well known. Chihuahua was made famous by National Geographic in 1921 when it featured the selenite Cave of Crystals/Cave of Swords. It revisited the site again in the 1990s. This second visit was broadcast on television as the selenite cave had the world’s largest selenite crystals — 40 feet long!
Also, the state of Zacatecas has certainly produced superb collector minerals including azurite, galena, sphalerite, chalcopyrite, and other metal ores. And, of course, silver species and gold have also come from here.
San Luis Potosi is very well known among collectors due to the superb poker chip calcite specimens it yielded in recent years. These specimens rival the historically important calcites from Germany. Quantities of large and sometimes colorful danburite crystals still come from here now and then as well.
In recent years, Sinaloa really caused a stir among collectors when the mine at Choix produced large quantities of colorful botryoidal smithsonite. Specimens up to a foot across were mined, and the color range seemed endless, from white to pink to yellow, blue, and green in various tints. Many of the Chiox smithsonite was easily mistaken for the famous blue specimens from Kelly Mine, New Mexico.
The range of collector minerals from Mexico in the last 75 years is simply amazing. From gorgeous Las Vigas amethyst crystal groups to recent Milpillas mine azurites to rare silver sulfosalts and everything in between, these finds enhance mineral collections worldwide.
The millions of mineral specimens brought to grass in Mexico have played a huge role in the growth of this hobby throughout the world in these last decades, and there is no end in sight.
Author: Bob Jones
Holds the Carnegie Mineralogical Award, is a member of the Rockhound Hall of Fame, and has been writing for Rock & Gem since its inception. He lectures about minerals, and has written several books and video scripts.