For anyone not familiar with mining terminology, an arrastre is a low technology method of pulverizing ore. From the perspective of production capacity, it is certainly a large step above panning for gold, but predates stamp mills, perhaps by hundreds of years. Although it was a slow and laborious method (at least for the mule), it was effective in separating free gold and silver from rock before more efficient ore crushing and chemical processes were developed. I believe the term “arrastre” is Spanish in origin but there is ample literature which refers to the method as Mexican arrastre. The technique was widely used in the early mining days of the Southwest and Mexico. In any case, it is definitely “pre-industrial” in nature.
The technique was relatively simple:
- Find a flat area of solid rock, several feet in diameter or
Construct a circular pit of appropriate size and line the bottom with clay topped with flat stones.
- Build a circular retaining wall of (vertical) stones or stout wood. The dimension of the ring will vary based on the space you have to work with. The vertical ring of wood or stone serves to keep the crushed ore inside.
- Insert a wooden pole or metal rod vertically in the center of the ring.
- Attach a horizontal pole to the vertical rod. It would have a length that extends beyond the diameter of the ring.
- Connect one or two mules to the horizontal pole — outside of the ring.
- Attach one or more drag rocks to the horizontal pole, inside the ring.
- Place ore to be crushed inside the ring.
- Put the mule(s) into first gear and drag the rocks around the circle to crush the ore.
Slow — yes. Effective — yes.
The historical literature states that drag stones weighed between 300 and 400 pounds. A single mule would have been able to drag two such stones. If more were used, then a second mule would have been required. I have found no references to the use of donkeys, although that probably can’t be ruled out in some instances. Mules are considerably stronger than donkeys, so they would have been the “horsepower” of choice.
The most graphic photo of an arrastre built on bedrock can be found at this web site: http://www.vtc.net/~buffalo/seazpics.html Scan down to the 5th photo to see this example.
Other examples in historical documents describe arrastres with flat bottom stones that were laid down on a bed of clay. (See reference 3 and 4 at the end of this article.)
The photo in the link above and the two depictions that follow represent only three of many ways that an arrastre could have been constructed. I suppose you could say the miners used whatever tools and resources that were available in the circumstance.
Figure 1: Depiction of Arrastre from 1867
Figure 1 is taken from a treatise titled “Mining and Metallurgy of Gold and Silver” by J.A. Phillips, dated 1867. It depicts an arrastre in the gold fields of California. See Reference #3 at end of article.
Figure 2: Depiction of Arrastre from 1862
Figure 2 has been reproduced from “The Mining and Smelting Magazine: A Monthly Review of Practical Mining, Quarrying, & Metallurgy, dated January-June 1862. The article in reference describes the “Mexican Method of Amalgamation.” It depicts an arrastre in Guanajuato Mexico. See Reference #4 at end.
The longer an arrastre was in operation, the more “discarded” drag rocks would be produced. You could logically infer that a long-used bedrock arrastre would become rather deep due to the continuous grinding of rock on rock. The drag rocks would become flat on one or more sides and would have one or two holes drilled on one surface where iron rods would be inserted. (Again, see photo on previous web link. This drag rock has a single iron rod rising from the top.)
It is important to mention at this point that the operation of an arrastre depended upon one other critical element for success, namely – mercury. This element would be added (in large quantities) to the pulverized ore to create an amalgam with the gold and silver. At various stages of the process, water would be poured into the arrastre to help create a paste that would slowly settle to the bottom. Eventually, the paste would be removed for further processing; which included squeezing the amalgam in a bag to retrieve as much of the mercury as possible.
I would, therefore, not want to characterize an old arrastre as “environmentally friendly.”
Arrastre East of Wickenburg
I am told that due to erosion, vandalism, etc., discovering an arrastre these days is a rather rare event.
The photo below (Figure 3) shows an arrastre located several miles east of Wickenburg that my son and I found in early 2007. There are several things to note in this picture:
- The ring of vertical stones is nearly circular. In fact, the dimensions are 112″ on the E-W axis and 108″ on the N-S axis.
- The area has been filled with sediment due to its proximity to a creek (left of photo) and uphill erosion (right of photo).
- Note the drag rock in the lower right foreground. See the hole drilled into the leading edge? This rock (and many others) would have been dragged around the inside of the ring to crush ore.
- Note also the rock to the right of the drag stone. It shows obvious evidence of having been used in the arrastre as well.
- Finally, note that the drag stone has a single hole drilled into the leading edge. This is similar to the drag stone at the arrastre in Cochise County.
Figure 3: Arrastre East of Wickenburg
I initially thought this might be a grave site due to the upright stone inside the ring (right center). Well, actually it isn’t. Although I vaguely remembered the term “arrastre” from years back, I had never actually seen one. Refer back to the techniques that I described in the introduction. An arrastre relies on two grinding surfaces – the underlying structure (whether bedrock or laid stones) and a drag stone. When you understand that principal, it is easy to see why you would be unlikely to find a burial inside an arrastre. There simply isn’t enough soil above the rock base.
Figure 4: Arrastre from opposite angle
The above photo (Figure 4) is a view of the arrastre from the opposite side. Note the rock in the lower right foreground. The left edge has clearly been ground into an arc, and was probably one of the ring stones at an earlier point in time.
I excavated the outer edge of one of the ring rocks on the north axis to a depth of about 8.5 inches and did not reach bedrock. This does not mean it was not a bedrock arrastre – it only means there was no bedrock at 8.5 inches. The excavation hole revealed reddish soil, which originated from the uphill side of the arrastre and not from the creek itself. The creek-side soil is a sand-gravel composition and is generally a light tan to gray color. I replaced the soil in the excavation hole after inspection.
Now, this is speculation on my part; but my guess is that an arrastre required more or less continuous maintenance due to the grinding effect of rock on rock. A fresh drag stone would not yet be smooth on one side, probably causing it to have a fairly erratic path around the inner course. It seems to me this would have been particularly true if there was only one drag point (drill hole). And, it also seems that the ore would have to be continuously swept back into the path of the drag stone. So, not disregarding the energy expenditure required by the mule, a full time attendant would have been needed.
If you closely compare the two drag rocks in Figure 3 and 5 (below), you will observe that each has only one drill hole. The 1860 era illustrations in Figures 1 and 2 depict drag stones that have two holes each.
Figure 5: Drag stones — and a surprise
There is considerable evidence of “discarded” drag rocks in both in the immediate vicinity of this arrastre and uphill (right and north) of the site. Figure 5, above, shows three more rocks, two of which have been ground quite flat on one side and probably no longer had sufficient weight to be effective in crushing ore. The drag stone in the foreground shows the characteristic drill hole where the iron rod would have been inserted. I have yet to find a drag rock at this location that has more than one hole.
As mentioned previously, I initially suspected the arrastre was a grave site. To gain expert insight, I contacted Neal Du Shane, president of the Arizona Pioneer Cemetery Research Project. (For more information on the fascinating historical and cemetery research that his organization does, please visit his website at: http://n.j.dushane.home.comcast.net/.)
After examination of my photos he advised me that the ring structure was a rare and very nice discovery; but that it was a pretty straightforward example of an arrastre. Nevertheless, he offered to investigate the site and surrounding area with me.
There are Graves!
Upon arrival at the site, Neal conducted a non-intrusive investigation of the arrastre. The method he uses is called “grave dowsing” and is quite effective in determining a burial site, its dimensions, and even the sex of the burial.
As he suspected, the arrastre was just that – an arrastre. Turning his attention to the area shown in Figure 5 above, he located two graves, both male. Figure 6 shows Neal documenting one of the graves. A preliminary outline of one grave has been established with a perimeter of small rocks that you see in the photo below. There are no inscriptions on any headstones. A hundred or more years ago, these graves may have had (though not necessarily) a perimeter outline of rocks. Neal states that cattle and other wildlife tend to scatter these outlines over time, however. The grave site is located approximately four feet above the creek to the left (south) of the photo.
Figure 6: Grave sites confirmed
Mining is a dangerous business and that would have been even more the case in the early days in Arizona. Where there are old mines, you can reasonably expect to find graves. Although the arrastre is some distance away, its function was directly connected to a mine in the area. I do not yet know if the arrastre coincided with or predated the mine. It is not beyond reason to think that ore from nearby locations could have been brought to the arrastre for processing as well. Without further documentation we may never know.
Above the hillside, to the right of the preceding photos, are the remains of two rock cabins, along with metallic surface debris (old cans, a stove, etc.). We climbed the hillside where I pointed out these structures to Neal. The surface of some of the rocks used in construction of the cabins had been ground flat and very likely came from the arrastre operation by the creek.
Not too distant from these cabins is another location that had a number of flattened arrastre rocks. When first discovered, these rocks seemed to be “out of place” with the immediate surroundings, however. There were no structures in the immediate vicinity, but it was adjacent to an old trail and was covered by a Palo Verde tree. See Figure 7 below.
Figure 7: Another grave site
Neal’s investigation of this site determined the presence of three graves – two female and one male. The orientation of these graves is on an east-west axis, whereas the two graves by the arrastre have a south-north axis (with the headstones being on the south). Due to the overgrowth at the upper location we did not determine if there were markings on any of the stones.
Known only to God?
I am told by Neal, Scott Rogers and others, who are much more knowledgeable of mining history than myself, that these mining pioneers were frequently interred in close proximity to where they died. A trip to Wickenburg, Octave or Stanton for burial would simply have been too long, and they might have been discovered days or even months after their death.
The names of some of these pioneers are well known (such as Isaac Bradshaw, who was buried within a few hundred feet of where he died). Others were both known and notorious. Some died violently, others died alone and unnoticed. Unfortunately, the identity of many others are now lost in time. The grave sites I have referenced in this article are recent discoveries, but that does not mean there is no history of these men and women who were early settlers in Arizona. Today, we can hardy imagine the dangers and hardships these pioneers faced – deprivation, illness, debilitating injuries and death.
At this stage of investigation there is no information about the five grave sites we have found. If you have knowledge about the history of graves east of the Wickenburg area, please contact Neal Du Shane to aid in his research at: firstname.lastname@example.org.
The names and histories of these individuals should be made known and remembered. The pioneers who lived and worked in this area are, for the most part, unnamed contributors to the legacy of history and economic progress that we now enjoy. The photos in this journal represent real history. These sites are already the victims of neglect and obliteration by cattle and wildlife. That isn’t vandalism — it is the actually the principal cause of the loss of historic grave sites.
It is not my intent to be mysterious or coy about the location of the arrastre and graves. The Arizona Pioneer Cemetery Research Project has marked the locations and, over time, will conduct research that could eventually lead to the identification of these five souls. All I ask is that you give the right people the appropriate time and space to conduct their research. The APCRP will publish these locations.
I had the pleasure of first visiting the mining camp of Tip Top in the southern Bradshaw Mountains in 1961. The main cemetery, which contained approximately twenty graves, was filled with headstones. They were, for the most part, fully legible. The miner’s cabins were intact and the well had very good water.
In the mid-1980’s I visited Tip Top for the last time. I wanted my son to see what a “real” ghost town looked like. Only one headstone remained and it had been blasted by a shotgun. The miner’s cabins were mostly destroyed and the well had been ruined by someone who had poured gas or oil into the water.
I can’t go back. I just wish I could remember the names.
Neal and his organization have spent two years researching the graves at Tip Top. If you would like to gain an appreciation of how difficult it can be to identify these pioneers, please visit his web site.
I am indebted to Jim Cook, Neal Du Shane and Martha Maxon for their kind assistance in the creation this article. Many thanks to you!
Article links and references:
- http://www.vtc.net/~buffalo/seazpics.html: Beth and Paul McKnight website – Cochise County, AZ. I have not been able to establish contact with the McKnight’s, but am listing their website in the belief they will appreciate this reference.
- http://n.j.dushane.home.comcast.net/: Arizona Pioneer Cemetery Research Project website. Managed by Neal Du Shane, President and Founder. Listed with permission.
- The Mining and Metallurgy of Gold and Silver: J. Arthur Phillips, 1867 – pg 165. This book is in the public domain and can be downloaded from Google.
- The Mining and Smelting Magazine: A Monthly Review of Practical Mining, Quarrying, & Metallurgy, and Record of the Mining and Metal Markets. Edited by Henry Curwen Salmon, January-June, 1862. Article referenced is titled “On the Mexican Method of Amalgamation” by James Napier – pg 166. This publication is in the public domain and can be downloaded from Google.
- Arizona State Parks – State Historic Preservation Office: (602) 542-4009. Public web site is: http://azparks.gov/partnerships/shpo/publicprog.html. This site describes the etiquette, laws and regulations governing archaeological sites, including graves.
Last 5 posts by Allan Hall
- Wickenburg Hospitality Comes in Many Forms - December 15th, 2010
- Calliandra Eriophylla is Native to the Wickenburg Area - December 9th, 2010
- Goodbye, Old Bridge - November 29th, 2010
- Abandoned Mines Part III: Preserving the "Whispering Ranch" Mine - March 25th, 2010
- Abandoned Mines Part II: Protective Closures - March 10th, 2010