Exploring Mexico’s New Classics: Adamite and Legrandite

This fine adamite specimen was bought for the huge sum of $2 in the 1960s. (ex-Bob Jones specimen)

Story and Photos by Bob Jones

Serious collectors can name most of the classic minerals. They would include silver from Kongs­berg, Norway; proustite from Chañarcillo, Chile; several sulfosalts from Germany; bournonite from Cornwall, England; azurite from Chessy, France; pink fluorite from the Alps; franklinite from New Jersey; stibnite from Japan and several others.

Designating 'Classic' Species

Fortunately, there have been occasions in the last few decades when a source was found whose speci­mens far exceed any known examples of the species, and those deserved the des­ignation of “classic”. Mapimi, Mexico, re­cently yielded two species deserving being called classics: adamite and legrandite crystals ranging from 1 to 3 inches, which diverged on a reddish-brown limonite matrix.

One such specimen that I was particularly familiar with was brought to Arizona by Benny Fenn in the 1970s. The legrandite was impressive, though the crystal spray was on a big—really big—chunk of reddish-brown limonite. The limonite matrix was a distraction. It was infused with silica, so it was difficult to break and trim. The owner finally decided to remove the legrandite carefully, trim the matrix to a good size, and replace the yellow spray by gluing it back in its original spot.

As exciting as the sporadic appearance of quantities of fine yellow legrandite specimens through the 1960s and ’70s was, the 1979 find confirmed legrandite as a classic.

Legrandite Helps Set Mina Ojuela's Reputation

A pocket opened in 1979 yielded a specimen I named the Aztec Sun in an article I wrote for

Legrandite-Aztec Sun
The author named this amazing legrandite the Aztec Sun when it was found. (ex-Romero collection)

Rock & Gem. This amazing speci­men is clearly the most famous legrandite of all, and it solidified Mina Ojuela’s reputation as something special.

Jack Amsbury, the mineral dealer who brought the specimen out of Mapimi, called me when he got back to the United States and invited me to Tucson to see this amazing specimen. That resulted in the /Rock & Gem article, the first to report on the specimen and give it the name Aztec Sun. The specimen was bought from Jack by our friend Miguel Romero. After Miguel’s death, his collection—including the Aztec Sun—was scheduled to go into the University of Arizona mineral collection. Due to some unfortunate circumstances, however, the collection was sold, ending up in a museum in the Near East!

Admiring the Aztec Sun

The Aztec Sun, the best legrandite ever found, is about 5 inches across and is composed of two complex crystal clusters that form opposing fanlike sprays. This beauty was joined four weeks later by another huge legrandite from the same pocket area. It is a single, narrow, diverging crystal cluster measuring nearly a foot long. At last report, it was in the New York Museum of Natural History.

The remarkable specimens of adamite and legrandite, both found in quantity at Mapimi, leave no doubt that this old silver mine will go down in collector history as a source of classic specimens.