Robert Safford Towne, Fresnillo
Amasa Delano Sproat, Guanajuato
William Hough Cook, Jr., Bellevue (1979)
Thence by descent

This painting has recently been restored. The stretcher is original but the canvas has been lined. The work is cleaned, varnished and retouched. There are retouches in the white archways in the center of the right side of the courtyard, where a damage has been repaired. There are also retouches in the hillside just to the right of the peak. These seem to be the only restorations in the lower portion of the work. None of the details in the foreground are compromised. The remainder of the retouches appear to be confined to the sky. In the lower right sky, there is a restoration about one inch by half an inch. There is retouching to random spots as well as to three significant losses in the upper right. These losses are roughly one inch by one inch each. In the center, there are two similarly sized restorations. In the upper left, there are again two similarly sized restorations, as well as a larger group of restorations further towards the upper left corner. Luckily, these restorations are isolated, and there has been no abrasion or diminishment of the palette or texture of the paint. The work should be hung as is. (This condition report has been provided courtesy of Simon Parkes Art Conservation, Inc.)
In response to your inquiry, we are pleased to provide you with a general report of the condition of the property described above. Since we are not professional conservators or restorers, we urge you to consult with a restorer or conservator of your choice who will be better able to provide a detailed, professional report. Prospective buyers should inspect each lot to satisfy themselves as to condition and must understand that any statement made by Sotheby's is merely a subjective qualified opinion.
NOTWITHSTANDING THIS REPORT OR ANY DISCUSSIONS CONCERNING CONDITION OF A LOT, ALL LOTS ARE OFFERED AND SOLD "AS IS" IN ACCORDANCE WITH THE CONDITIONS OF SALE PRINTED IN THE CATALOGUE.

The present painting depicts a large, enclosed court­yard in which men and animals are engaged in various mineral processing activities. The dark-colored disks on the patio floor contain a semi-liquid mass of pulverized, low-grade silver ore that has been mixed with several reactive agents, most notably mercury. These ore masses were central to a silver reduc­tion method known as the Patio Process, which was developed in sixteenth-century Spain and used for approximately 350 years.

The building itself was named the Hacienda Nueva de Fresnillo, (Fresnillo’s new processing plant), or the Hacienda Grande, (great or large processing plant), depending on which source one refers to. Built in 1840, it was considered to ℱbe the best of its kind in the world.

The conical hill in the background is Proaño Hill, or Cerro de Proaño in Spanish. It contai⭕ns a rich network of silver veins and remains a pr🌟ominent landmark near the mining town of Fresnillo.

Salient features of the scene depicted in the 1846 Gualdi painting: The Gualdi painting depicts a now-obsolete silver reduction method called the Patio Process, (termed Beneficio de Patio in Spanish). This proc🔜ess was developed in Spain in the sixteenth century and was in use for about 350 years. The Patio Process was so-named because operations were centered inside a large, open courtyard. Finely disseminated silver particles were extracted from low grade ore by (1) crushing and grinding blocks of ore iꦕnto powder form, (2) producing a mercury-silver amalgam, in which silver is alloyed to mercury through a series of chemical reactions, (3) washing away the rock and dirt particles, and (4) evaporating the mercury to leave the silver in concentrate. 

As illustrated in this painting, horses w🌳ere driven through the ore masses on the patio floor. The mixing action caused by their hooves accelerated the chemical reactions necessary for alloying silver to mercury. This process facilitated the isolation of finely disseminated silver particles from surrounding d𒆙irt and rock. In subsequent steps the mercury was evaporated to leave the silver in concentrate, pure enough to be melted into ingots and delivered to the government mint.

 Lower-front-center detail of the Gualdi painting: The area’s great mineral wealth first came to the attention of Europeans during the early years of the Spanish Conquest. When Gualdi completed this painting in 1846, mining operations at Proaño Hill were in full swing due to the installation of expensive, Cornish pumps, imported from Europe, which dewatered the deeper shafts and thus enable꧟d access to large quantities of low grade silver ore. At the time, the mine and processing plant were under the control of the Zacatecas State government. Presumably, Gualdi was commissioned by the state to paint this scene.

The silver veins at Proaño Hill extend to great depths and branch eastward towards the town of Fresnillo.[i]The principal veins run northwest and southeast, almost pa🅰rallel to the line of the hill's maximum slop✃e.

Historically, the silver-bearing ores mined at Proaño Hill were of three classes. First there were the Coloradas, meaning reddish in hue. The Coloradas occurred only in the upper levels, never deeper than about 220 to 250 feet, and were gen♍erally soft. The value of these oxide ores was difficult to determine by eye because the silver was finely disseminated throughout the ground mass.

The second group of ores was called the Negros and they were unknown during the earliest years of mining.  They were darker or blackish in color, (negro is the Spanish word for black). Generally, the Negros were soft and occurred just below the Coloradas.  The Negros formed the major part of the ore product and their value increased with depth. Generally, they occurred as a compact iron­ bearing rock carrying variable quantities of silver, either metallic or as sulphides. These minerals were easily distinguished from the Coloradas by thei🌠r weight and metallic characteristics. In some horizons, silver­-bearing chalcopyrite was encountered.

The third group of ores, known as Azogues, (Spanish for mercury or quicksilver), did not occur in vein but rather in country rock on both sides of the vein for a distance of 1½ feet. The Azogues carried metallic silver as well as its sulphides and chlorides, disseminated in minute particles. Values of these ores were even more difficult to determine by eye than those of the Coloradas. The gold content of all the ores was very slight and had no effect on ge🔯neral ore values.

The silver processing plant pictured in the Gualdi painting was built in 1840. It was referred to as the Hacienda Nueva de Fresnillo, i.e., Fresnillo’s New Processing Plant, or the Hacienda Grande, meaning, great or large. The generalized Spanish term for “processing plant” is hacienda de beneficio. In Zacatecas, such a plant also was called an incorporado, referring to the place where mercury was incorporated into the silver-bearing ore.[iii]

Located a short distance west of the base of Proaño Hill, the Hacienda Grande featured a huge square patio that measured 1,150 feet on each side. It had a capacity for 64 tortas or more, depending on the floor plan, (in this context, the Spanish term torta refers to the partially processed silver ore that was contained in round, shallow pits dug out of the ground- torta is a Spanish word meaning pancake or pie). In its heyday during the mid-nineteenth century, the Hacienda Grande at Fresnillo represented the apogee of Patio Process 🙈technology and was considered to be the most extensive and best arranged metallurgical plꦜant in the world.

Gualdi was born on July 22, 1808 in northern Italy, in Carpi, Modena province.[iv]Around 1834-35 he studied at the Academia in Milan where he studied perspective, painting and theater design. Around 1838 he accompanied an Italian opera company to Mexico where he  would remain for about a dozen years. Besides being a designer of theater sets, Gualdi was a prolific sketcher and painter of architecture, landm🎀arks and urban scenes. His Mexican work generally depicts exterior scenes of Mexico City and monumental interiors, all rendered with exacting, architectural detail and accurate perspective in the classical European 🌸tradition.

Gualdi published and album of lithographs of Mexico City’s most famous building in 1841.[v]Gualdi also published individual lithographs. He taught perspective at the Academia de San Carlos 1850, Carlos in Mexico Ci𓆉ty and shortly the♓reafter left to work in New Orleans.

[i]These facts abꦫout the mining history at Proaño Hill are drawn principally from the following book:

Kemp, Donald C. Quicksilver to Bar Silver: Tales of Mexico’s Silver Bonanzas. Pasadena: Socio-Technical Publications, 1972; chapter six, “Sombrerete and Fresnillo”, pp. 115-13♚2

T🐠his chapter appears🌺 to rely on a document produced in 1883:

Silliman, Benjamin (1779-1864). Sketch of the Great Historic Mines of the Cerro de Proaño at Fresnillo, State of Zacatecas, Mexico (1883).

[ii]Original photos of the Hacienda Grande and P♒roaño Hill taken circa 1910 by Amasa D. Sproat; W.H. Cook family archi🍷ves.

[iii]Bakewell, P.J. Silver Mining and Society in Colonial Mexico, Zacatecas 1546-1700. Cambridge: Cambridge University Press, 1⛦971, 140

[iv]Gualdi biographical facts: Palmquist, Peter E. & Kailbourn, Thomas R. Pioneer Photographs From The Mississippi to the Continental Divide – A Biographical Dictionary, 1839-1865. Stanford, California:💃 Stanford University Press, 2005, pp. 291-🗹292.

[v]Monumentos de Mexico, tomados del natural y grabados por Pedro Gualdi, printed by Massé y Decaen, 1841.