The Silver Mines of Hostotipaquillo Part 5 of 10: Ex-Hacienda Mochitiltic (the silver refinery)

A view toward the mountains through the arches next to the refining operation. In this posting, I will continue with my exploration of the ruins of Ex-Hacienda Mochitiltic. Last time I focused on the casa grande and capilla, but in this one we'll look at the aqueduct, the water wheel, the great furnaces, and the patio where the mercury amalgamation process occurred.

This hacienda had a 300 year history, beginning in the 17th century and ending in the early 20th. Most of the historical references I have found are from the 18th century. They refer to its function as a hacienda de ganado y agricola (livestock and grain). The owner, Juan Fernández de Ubiarco, used the food, leather, and livestock it produced to supply his mines and haciendas de beneficio (ore refineries). 

Then, sometime later, structures were added which transformed Mochitiltic into a hacienda de beneficio. The food and livestock operations may have continued, but that is not clear from the available information. Today, the whole operation is in ruins, but there is more than enough left to deduce how the refinery operated.

Google satellite view of the ex-hacienda. The pueblo of La Venta de Mochitiltic is to the north, or top, side of the photo. For information on how to find this site, refer to Part 4 of this series. The road through the pueblo leads down a hillside through the clump of trees in the top center. Just below the trees is an open area which contains the arches seen in the first photos of this posting. The ruins are located on either side of the road. The casa grande structures, shown in Part 4, are located diagonally across the bottom-right quarter of this photo. 

Just left of center is a large open square that was the patio of the refinery. The left side of the square is bordered by the water wheel. This was fed from an aqueduct that can be seen running from the upper left corner of the patio to the top center of the photo. The furnace room is located on the south side of the patio and the furnaces are along the south wall of this room. The capilla (chapel) from Part 4 borders the right side of the patio and furnace room. 

The Aqueduct

The aqueduct runs downhill to the water wheel from a holding pond fed by a spring. It is a rough stone structure about 1m (3ft) high for much of its length, although it gets much higher as it stretches down the hill (toward the top of the photo). You can see the trough, now full of leaves, where the water once flowed. Water was always a necessity for food and livestock haciendas, but it was also a critical element in silver refining. It provided both a source of power and a key element in the chemical process used in refining the ore. Consequently, haciendas de beneficio were always built near an arroyo, a river, or some other ready source of water.

This arch forms an opening in the aqueduct to allow people and animals to pass. At this point, the aqueduct is about 4m (12ft) high. A few meters to the left, it spills onto the water wheel, which turned the machinery to crush the ore. Aqueducts have a very long history, having been used by ancient people in the Indus Valley, Egypt, Mesopotamia, Greece, and Rome. This method of transporting water actually dates back as far as the 7th century BC, when the Assyrians built a 300 mile aqueduct to bring water to Nineveh, their capital city. 

The trough of the aqueduct is lined with mortared bricks to prevent leakage. At the point above, the aqueduct is very near where it ends at the water wheel. The wall that supports the trough was built with rough stone, probably gathered from the stream bed at the bottom of the hill. I have often found old aqueducts (although not this one) which are still carrying water even when the rest of a hacienda lies in ruins. They were built to last, which indicates their importance. 

The Water Wheel

The huge water wheel turned between two high walls. A friend took this shot of me as I photographed the interior space between the two walls. It is not my most flattering pose, but it does show the opening through which the wheel could be inspected as it turned. The wheel is long gone, but it must have been very large, given the height of the walls and the depth that the turning space extends into the ground

Harnessing the power of water through the use of wheels also has a very ancient history. The earliest-known water wheels were invented in Mesopotamia in the 4th century BC. The basic concept didn't change until the mid-19th century when engineers discovered they could produce electricity through water power. Modern hydro-electric dams still use water power to produce electricity by turning turbines.

Interior of the water wheel's support structure. As the wheel turned, water flowed off its paddles and out through this spillway to the stream below. The two walls stand about a meter apart and the slot extends into the ground about 2 meters below the opening through which I was looking. Even after a couple of centuries, the walls still appear to be solid and relatively smooth. As I said, the colonial engineers built to last.

The support base for the equipment powered by the water wheel. The axis of the wheel would have extended out from the opening in the wall to the ore-crushing machinery mounted on the base. Originally, the machinery would have been made of wood and leather and seated on the stone foundation. This would have included a grind stone to crush the ore. The metal base you see above is a product of the late 19th or early 20th centuries. It probably supported a generator to  transform water power into electric power. 

The Patio

The doorway of the north wall, viewed from inside the patio looking out. Like the casa grande, the lower part of this wall was made with rough stone, while the upper was made with adobe. The door was trimmed with brick. The whole structure was once covered with plaster, the remains of which can still be seen on and around the door frame. This wall borders the north side of the patio. A few meters on the other side of the door is the set of arches I have shown previously.

Today, the ground slopes upward toward the north wall, but the area within the patio was originally level. The slope was likely created by erosion from uphill which swept earth and debris down into the patio. This was an area where one of the most important stages of silver ore refining occurred, called "the patio process". 

View of the northeast corner of the patio. The patio's area is approximately 30m (98ft) square. After it was extracted from the mine, the ore was broken up into smaller pieces, sometimes by women and children. It was then hauled down to the hacienda de beneficio by pack-trains of mules. Once here, it was further crushed by the water-wheel's machinery. This gave the ore a consistency that was somewhere between fine gravel and a coarse powder. It was then spread out in the patio in the shape of a huge pancake a few centimeters thick.

Next, mercury was sprinkled over the pancake along with a salt-water brine. This was mixed into the pancake using the feet of horses or mules. Even human feet were sometimes used. The highly toxic nature of mercury was not known at that time, so both animals and humans no doubt suffered negative health effects. However, the life-spans of workers and draft animals in the mining industry were already short due to accidents and the effects of mine dust. It is possible that the cumulative effects of mercury poisoning were not that noticeable in those days.

The Furnaces

Vinnie and I inspect the lower end of the ruins. Vinnie (left) is not only a fellow Hacienda Hunter, but my next door neighbor and an excellent photographer. The arch you can see over Vinnie's shoulder is the opening of one of several furnaces that were used as part of the refining process. The long wall extending behind me is part of the capilla seen in the Part 4 of this series. (Photo by unknown Hacienda Hunter).

The south wall of the furnace room, showing one of several chimneys. The walls on this end of the ruins are 4-5m (12-15ft) hight. A few meters behind me when I took this shot is the stream into which the water wheel once emptied. Thorny underbrush covers much of this part of the refinery ruins. We had to move carefully through here while taking photographs lest we get thoroughly scratched.  I have often found the thorny plants in Mexico to be actively hostile. Consequently, I always advise participants in these adventures to wear long pants and boots. 

View of one of the furnaces. Like water, heat was important to the process of silver refining. In the very early days, heat was used to melt silver from ore. However, this only worked well with high-grade ore and, as that was exhausted, silver production began to decline. Then, in 1554, a man named Bartolomé de Medina immigrated to Nueva España (Mexico). He brought with him a new refining process called amalgamation, which used mercury and salt brine on lower-grade ore and allowed it to be refined into high-grade silver.

After it was mixed into the pancake, the mercury and silver amalgamated and then sank to the bottom where it could be recovered. Next. the amalgam was heated to evaporate the mercury, leaving nearly pure silver. Over time, this "patio process" revived the colonial mining industry and allowed the re-opening of mines that had been closed as unprofitable. However, the heat process continued well into the 18th century at some of the haciendas de beneficio around Hostotipaquillo. 

Vent hole in the wall between two of the furnace openings. The furnaces, chimneys, and a good part of the south wall are made of bricks. This means that they were built fairly late, probably in the 19th century. Before then, bricks were too expensive to be used on a large scale. This fits with the hacienda being converted from an agricultural and livestock operation to a refinery in about that time frame. However, this is only my informed speculation, based on my knowledge of what building materials tended to be used in different periods.

Furnace Room

Jim B explores the furnace room. The door behind him faces the wall with the water-wheel. The room is one-story with a tall ceiling. I concluded this from the absence of a line of rafter holes in the walls. Such holes are always present when a room had two or more stories. The triangular windows above the door are unusual. I don't recall seeing any like this before. The wall behind Jim B and the one on the right are still mostly covered by the original plaster.

The silver-mercury amalgam would have been recovered on the patio and brought into this room to be heated. After the mercury burned off, the molten silver would be cast into ingots. When they cooled, the ingots would then be loaded on to mule pack-trains for shipment to Guadalajara and then on to Mexico City. From there, it would have either been shipped to Vera Cruz and on to Spain, or to one of Nueva España's Pacific ports for shipment to Manila and from there to China. Ex-Hacienda Mochitiltic was one part of an international trade network.

An eerie face is carved into the window support on the south wall. Somehow, I missed this odd feature while photographing the furnace room. Two of my fellow Hacienda Hunters each spotted it and took their own shots, one of which appears above. The face seems vaguely pre-hispanic, but how it ended up in this room remains another of Mochitiltic's mysteries. Perhaps it was a piece of old pre-hispanic masonry that was lying about. It also could have been the product of some 19th century mason's sense of humor. (Photo by Bette Brazel)

Jim B, his exploration finished, mounts the stairs leading to the patio. Notice how thick the walls are in the doorway. Across the patio you can see the door in its north wall that I showed previously. The walls here are constructed of large unfinished stones, indicating that this part of the furnace room may have been constructed in the 18th century or even the 17th. In that case, the room may have originally had some function that preceded its use for silver refining.

A curious horse came over to inspect our group. He was very friendly and obviously happy for a break in his usual routine. This shot was taken during my first visit in 2016, when several horses were present. When we visited in 2023, none were around, although they may have been somewhere else at the time. Behind the horse you can see part of the aqueduct.

This completes Part 5 of my Hostotipaquillo series and the last part of my two postings on Ex-Hacienda Mochitiltic. I hope you have enjoyed visiting this old site. If so, please leave any thoughts or questions in the Comments section below or email me directly. If you leave a question, please include your email address so that I may respond in a timely manner.

Hasta luego, Jim