Rio Arriba County

Shop Rio Arriba Minerals HERE

If you’ve ever been to Abiquiu, New Mexico, to visit the landscape that Georgie O’Keefe made famous in many of her paintings, you’ve been to Rio Arriba County. Stretching from just north of Los Alamos to the Colorado state line, and roughly from Espanola west towards Farmington, this county’s geology and mineralogy are varied and complex.

 Its history and culture is also varied and complex. “Rio Arriba” means “upper river” – and the river happens to be the Rio Grande. This designation originated in 1821 when the Mexican territory was divided into two halves, the “upper” and “lower” rivers. As described in the Rio Arriba County government website, most of the people and nearly all the wealth went to the Rio Abajo (Santa Fe and south), and the Rio Arriba

“ the forgotten “Upper River,” evolved into a creative, diverse, isolated, shunned, independent, self-reliant, and quirky cultural mix.”  (read more HERE).

Similar to adjacent Taos County, the rocks of Rio Arriba County range from geologically young Rio Grande rift-related volcanism to Triassic sedimentary units with abundant fossils and copper mineralization to Precambrian pegmatite deposits. Gold and silver have also been found in some of the prospects.

A short article summarizing the minerals of Rio Arriba County can be found HERE.

Mining Districts in Rio Arriba County*

Abiquiu district - Azurite, bornite, chabazite, chalcocite, halotrichite, labradorite, limonite, malachite, olivine, pickeringite, pyrolusite, quartz, sanidine

Bromide No. 2 district - Allanite, azurite, biotite, bromargyrite, calcite, chalcopyrite, chlorargyrite, chlorite, copper, covellite, cuprite, epidote, fluorite, freibergite, galena, gold, hematite, hornblende, kyanite, limonite, magnetite, malachite, metatorbernite, molybdenite, muscovite, pyrite, quartz, rutile, sabugalite, siderite, sphalerite, stephanite, tetrahedrite, tourmaline, uraninite, xenotime

Gallina district - Azurite, barite, bornite, chalcocite, covellite, gypsum, malachite, quartz

Hopewell district - Azurite, biotite, calcite, chalcopyrite, chlorite, cuprite, galena, gold, hematite, hornblende, limonite, magnetite, malachite, muscovite, pyrite, quartz, rutile, siderite, sphalerite, tourmaline

Ojo Caliente No. 1 district - Albite, andalusite, barite, beryl, biotite, bismutite, calcite, columbite-tantalite, fluorite, garnet, gold, hematite, kyanite, limonite, microcline, monazite, muscovite, orthoclase, quartz, samarskite, schorl, silver, spessartine, staurolite

Petaca district - Actinolite, aeschynite, albite, almandine, andalusite, apatite, azurite, beryl, biotite, bismuth, mismuthinite, bismutite, bornite, calcite, cassiterite, chalcedony, chalcocite, chalcopyrite, chlorite, chrysoberyl, chrysocolla, clinochlore, clinozoisite, columbite-0tantalite, covellite, cuprite, dumortierite, epidote, euxenite, fergusonite, fluorite, gadolinite, gahnite, galena, garnet, gummite, hematite, heulandite, hornblende, ilmenite, kaolinite, kyanite, lepidolite, limonite, magnetite, malachite, manganocolumbite, microcline, molybdenite, monazite, mordenite, muscovite, oligoclase, opal, orthoclase, phlogopite, psilomelane, pyrite, pyrophyllite, quartz, roscoelite, samarskite, scheelite, schorl, serpentine, sillimanite, spessartine, staurolite, talc, titanite, topaz, tourmaline, uraninite, uranophane, yttrotantalite, zircon, zoisite

Stinking Lake district - Rutile, schorl, zircon

Rio Arriba Minerals at Taos Rockers

The selection of minerals at Taos Rockers varies over time; following are some that are usually in stock. Click HERE for available items.

Columbite from the Petaca District

Columbite is a rare-earth mineral, so called because it has high concentrations of the relatively rare element Nb (niobium); its formula is Fe²⁺Nb₂O₆

Most columbite is found in granitic pegmatites and the Petaca District columbite is no exception. The pegmatite was originally mined for its mica, particularly large books of muscovite that were used for window panes and stove doors (heat resistant), and later for electrical uses. The pegmatites of this district occur in Precambrian igneous and metamorphic rocks, similar to the Harding Pegmatite.   

“Poker Chip” Calcite from the La Madera District

Calcite is a common secondary mineral in basalts, forming fracture and vug fillings. The “poker chip” calcite from the Hinsdale Basalts in the La Madera District has a distinctive crystal habit of large plates that overlap, looking something like a pile of poker chips. The Hinsdale Basalts are older than the adjacent Rio Grande rift-related basalts, forming the youngest unit of the San Juan Volcanic field, ranging from about 5 to 27 million years in age.

Fluorite and Barite from the El Rito District

Extensive fluorite and barite deposits occur in the El Rito District, related to secondary mineralization associated with basaltic volcanism similar to fluorite deposits associated in the more southern New Mexico counties. The deposits were large enough to be considered for economic development; the Small Fry Prospect is one such mining claim. It was abandoned when it was determined to not be economically viable and is open to public collecting.

An excellent short video on collecting at the Small Fry can be found HERE.