Mojina Mine, Rancho de Mojina, Ricardo Flores Magón, Mun. de Buenaventura, Chihuahua, Mexico
|Latitude & Longitude (WGS84):||29° 54' 7'' North , 106° 51' 14'' West|
|Latitude & Longitude (decimal):||29.90194,-106.85389|
|Köppen climate type:||BSk : Hot semi-arid (steppe) climate|
Panczner (1987) places the locality in Ejido Constitucion, Municipio de Ahumada...but the locality is actually in Municipio de Buenaventura, the next Municipio to the west. Constitucion is very small (<300 inhabitants) and town of Ricardo Flores Magon (>3000 inhabitants) is only a few kilometres farther away and readily locatable on worldwide maps. Access to the mine is strictly controlled by the property owner from either Constitucion or Ricardo Flores Magon.
Mina Mojina (The Mojina Mine) is a classic carbonate replacement deposit that lies about 2/3rds of the way between Santa Eulalia and San Pedro Corralitos in north-central Chihuahua. It sits about 100km west of Villa Ahumada. Mojina produced high-grade oxide lead-silver-zinc ores with minor gold and tellurium from mantos located on the upper and lower contacts of a felsic sill. The mine intersected a series of caverns lined with calcite...most were the "popcorn" like growths. Rarer were pockets lined with "cobra-calcite" ...well crystallized calcite with distinctive curved rhombs up to 3-4 cm across that look like upright cobras with their hoods spread. Some of these have sharp blue celestine crystals on them...Never a big mine, it might have produced 100,000 tonnes.
Benny Fenn brought very large quantities of specimens out of the mine in the late 1960s, selling most through Suzie Davis in Tucson (Benny Fenn, personal communication). Virtually nothing has emerged since given difficulty of surface access.
Note that although there are naturally lustrous calcite specimens from the locality, many have been washed with hydrochloric acid to remove an outer fine-grained layer of "dusty" matte luster calcite and give them a glossier luster. These latter can best be identified by looking for patches of matte luster or examining the point of attachment to see if the edges are rounded or if what should be sharp cleavage planes are etched.
4 valid minerals. 1 erroneous literature entry.
This geological map and associated information on rock units at or nearby to the coordinates given for this locality is based on relatively small scale geological maps provided by various national Geological Surveys. This does not necessarily represent the complete geology at this locality but it gives a background for the region in which it is found.
Click on geological units on the map for more information. Click here to view full-screen map on Macrostrat.org
100.5 - 145 Ma