Duane's take
Here's how the official marker tells it, and I'll do my best to do it justice. Back in 1756, the Governor of Spanish Texas had a job that needed doing, and he handed it to a man named Bernardo de Miranda. The commission was straightforward enough on paper: go examine a place called Cerro del Almagre, a red ochre hill that was supposedly rich in silver.
Supposedly. That word right there ought to give you pause. Miranda didn't go alone.
He rode out with a party of twenty-three, setting off from San Antonio, and somewhere along the way they struck Honey Creek, right near where you're passing through Llano County today. From there the party pushed on to the junction of the Llano and Colorado rivers. Now, you have to imagine what that kind of journey looked like, twenty-three men on the frontier, chasing a rumor of silver glittering inside a hill the color of dried blood.
They made it to Cerro del Almagre, they got their hands on the ore, and they hauled out three pounds of it. Three pounds. That went to assay, and the numbers came back.
For every hundred pounds of ore, the hill gave up ten ounces of silver. Ten ounces. The red hill had made a very large promise and delivered a very small return.
Plans for further explorations were abandoned. The low yield was bad enough on its own, but you stack on top of that the problems of transporting anything out of that country, and then add the very real threat posed by the Indian presence in the region, and suddenly that glittering rumor just wasn't worth the cost. Cerro del Almagre kept its secrets, and Bernardo de Miranda rode back the way he came.
What the marker says
By commission of the Governor of Spanish Texas, Bernardo de Miranda in 1756 examined Cerro del Almagre, a red ochre hill supposedly rich in silver. His party of 23 from San Antonio struck Honey Creek near here, then went to the junction of the Llano and Colorado rivers. Three pounds of ore from Cerro del Almagre assayed only ten ounces of silver to 100 pounds of ore. Plans for further explorations were therefore abandoned as such low yield; coupled with transport problems and Indian threats, made mining seem unattractive.