Texas geology and random prospecting

In the 1840’s a geologist in a group of incoming German settlers to the Texas hill country noted that, despite rumors of silver around the San Saba River, the area was limestone and minerals in limestone would be unprecedented.  In more recent times people have looked around and noted that it was a limestone area, and that was that–any prospecting for minerals was a fool’s errand.

Limestone is a type of sedimentary rock, in particular the geological remains of ancient ocean beds. Over time the calcium-rich coral and such formed limestone.  Silver, gold, and that sort of thing is not to be found in limestone.  Limestone is good for making gravel, cooking into quicklime for cement, cooking into lime to adjust the acidity of farm land , and for a few other things.  And that is about it–a bulk commodity.  As a child growing up in south-east New Mexico, I was disappointed to learn that our corner of the state was atop this miserly substance called limestone.  That meant that no rocks on the few acres the family owned were of any value.  All those interesting rocks in the Golden Guide to Rocks and Minerals were no where to be found, and no gold nuggets waited to be dug up from the back yard either.  Although, since digging through the caliche under the few inches of top soil there was about like digging through a brick wall, opening a back yard mine would have been challenging anyway.

The consolation prize that goes with mineral barren limestone areas are caves.   Over many centuries water can turn a bed of limestone into a cavern.  Treasures of their own sort that people can enjoy.  And there are a couple of limestone caves around Menard that figure into the treasure story.

But back to the 1840’s, the German geologist did not say that minerals in limestone was impossible, rather he said that it would be unprecedented.  Sometimes unprecedented things happen–the best hope for minerals to be found in a limestone area is for volcanic activity to have pushed up from under the sedimentary rock.  So, maybe it is not entirely impossible, but just very highly improbable that one could find valuable minerals in limestone.

If, in centuries past, limestone meant no minerals, would anyone in the Spanish Colonial era have bothered to prospect in the immediate area?  The answer is yes.

There is silver in Texas, and Texas used to have active silver mines, albeit not from around Menard.  But it was and is a drop in the bucket compared to the silver in Mexico. The silver mines in Mexico were not a dozen people digging out some ore from a fifty foot hole in the ground, to then smelt in a large outdoor oven.  In Mexico mines used thousands of workers and the refineries were complexes covering dozens of acres. Most refineries ended up using the mercury patio process, while others used the charcoal furnace process when the cost of mercury was greater than the gain from the increased recovery of silver.

In the 1700’s the miners in Mexico had a quota of so many bags of ore per day.  Then they could fill a bag or two for themselves.  They would then take their own bags of ore to an independent refiner for extra income.  If a person knew what they were doing it did not take much to set up a crude smelter in a small area.  The mine owners did not like that. They complained that the choice, high grade, ore went into the bags of the miners.  The miners complained that they were poorly paid for the hard and dangerous work they did.  In such circumstances workers start complaining, and the complaining spreads, and words turn to actions. That was good for neither the wealthy mine owners nor the tax revenue of the Spanish crown.

There was a way to deal with labor agitators: send them to Texas to be Presidio soldiers.   That would get them out of Mexico, away from the mines, for years.  Not all soldiers were ex-miners, but some were.   They were not trained geologists.  It is not at all condescending to suspect that they did not know the difference between sedimentary rock and igneous rock and any other kind of rock.  Most people today could not tell the difference either.  To them rock was just something to dig through to find ore.

Presidio commanders were notorious for getting rich off of the Spanish Crown while the soldiers were given low wages.  The soldiers were not paid by the Crown, rather the commander was.  The wages to the soldiers were not even real wages, but script to the company store.  A store owned by the commander.  Soldiers often served beyond the normal retirement age of soldiers because they  could not pay off their debts to the commander.  It seems reasonable that they would spend their free time prospecting. Finding a rich mine might be the ticket to paying off their debts and retiring, maybe even retiring well.  And they knew how to dig holes in the ground.  They did not know that limestone was supposed to be a fool’s errand.  So they probably dug holes here and there as they could, preferably within running distance of the Presidio lest the Comanche turn up and turn the exploratory shaft into a mass grave.

So it seems likely that a number of randomly placed exploratory shafts would have been sunk in a several mile radius around the Presidio on the San Saba River.  In more recent times they have possibly been found by treasure hunters who took them to surely be the remains of rich mines that were abandoned after Indian massacres. Could be, or could be soldiers who desperately wanted to find a vein of silver that would be their ticket to an easy life back in Mexico.  Apparently one such hole was found not that many decades ago near the Menard water tower.  Perhaps Gooch’s Folly was another.

There are many old newspaper articles about someone in Menard County who found a hole on their land, and was just sure that was the mine.  Then nothing more came of it. At first I suspected that they were all part of schemes to sell mining stock. But perhaps they were more often the honest discovery of a somewhat random exploratory shaft that miners-turned-soldiers hoped would be their ticket back to Mexico a century and a half earlier.

2 thoughts on “Texas geology and random prospecting

  1. Very well written and informative. That would account for some of the holes people have found in limestone.


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