The Santa Brigida Mine
Cresting a dirt road hill, the appearance of three pyramids alerts Paul and me that we have arrived at the Santa Brigida Mine. To my eye, their purpose is unmistakeable: they have to be smelters. Within, fires burned fiercely under piles of silver ore. Tall chimneys provided lots of draft, raising the temperature of burning charcoal enough to melt silver.
Draft is one form of controlled air movement. Draft can be used to provide oxygen for combustion or for respiration. The builders of Santa Brigida Mine were masters at controlling airflow.
Photo: Paul Latoures
Raymondo, our self-appointed guide and teacher explained all this to us. Raymondo is the last miner in Pozos. He was working at this mine when it closed in 1965.
I wanted to know what metals were mined here besides silver.
“Lead, mercury, copper, bronze (he meant tin), and iron.”
“Was the mercury used to separate out gold?” I asked.
“No, Señor. Para bombas atomicos.” Sheesh.
Photo: Paul Latoures
Raymondo explained that the small smokestack and some associated rusting cylinders were parts of a system for pumping air into mine shafts. This and the ruins of a small hospital give thin evidence of the owner’s concern for the miners’ welfare. During Santa Brigida’s heyday, more than a hundred miners were injured every year. Three or four of them died. Children hauled ore to the surface in wicker baskets—even into the 20th century.
The main reason I wanted to explore this particular mine was the rumored existence of El Túnel de los Vientos—a passive device for creating huge amount of draft. Paul’s photo captures about a quarter of the tunnel’s length. The figure at the end is me, aiming my camera toward a hole in the roof at the up-wind end of the tunnel.
Photo: Paul Latoures
The wind tunnel is constructed of stone. It is nearly 600’ long. A series of archways pierce one side of it every 30’ or so to admit outside air. Baffles alternate left and right, forcing air moving through the tunnel to veer away from each archway so that ever more is pulled into the tunnel at each opening.
Air movement through the tunnel is initiated by building a great charcoal fire at the downstream end. As the fire begins to draw, airstreams from all the side openings combine to create a mighty blast, forcing the charcoal to burn at white heat—hot enough to smelt iron ore.
El Túnel de los Vientos is a fine example of mid-19th-Century technology. Its design required thinking every bit as sophisticated as that of many 21st-Century engineers. (And, may I add, way more sophisticated than the design my of Mac’s power cord.)
Exploring and deciphering objects like this old wind tunnel just thrills me. But then, as nerdy teenagers, my friends and I used to chuckle at camshafts with radical grinds. I really haven’t matured much, these last sixty years.
About the scene I was shooting when Paul caught me pointing my camera upward: here it is. I took it looking straight up at the tunnel’s only roof air inlet. I include it here because I think it looks kind of cool.
Ownership of the Santa Brigida Mine is in dispute. Raymondo says that when the owner died eighty years ago, an interloper squatted on the land and initiated legal processes to validate his claim. Proceedings have dragged on for decades, and I imagine will continue for many more years. Well-placed individuals with strong financial resources can keep issues simmering in dysfunctional Mexican courts indefinitely, sometimes winning through attrition if not by merit.
Meanwhile, someone is maintaining the owner’s mansion. No one lives there now, but if ownership of the mine is ever settled, it’ll be there waiting for the victor.
The land surrounding Pozos is an ecological disaster, as is much of the Bajio. In the Seventeenth Century the owner’s mansion would have been surrounded by trees instead of the present-day scrub and cactus. But all the trees have been cut, principally for making charcoal. (Note: The Atlantic seaboard east of the Appalachians was once covered by an ancient forest. It too was cut for iron-making using charcoal.)
Soil, no longer secured by plant roots, washes into watercourses with every rainfall. Ponds, lakes and reservoirs fill with silt, their waters gray from suspended clay particles. Piles of spoil slump across the landscape: sterile heaps upon which nothing will grow in our lifetimes.
I have heard no reports of heavy metal contamination of the water table, but such pollution nearly always accompanies mining operations. The absence of reports of groundwater contamination almost surely is attributable to no one bothering to investigate. A mine may look like no more than a hole in the ground, but excavating and processing ore is incredibly destructive to the environment.
The Santa Brigida Mine is one of 500 surrounding Pozos. It’s one of thousands scattered from Zacatecas on south. Their presence has contributed to the desertification of central Mexico.