Gypsum Interpretation Center 3/6

Extraction area

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Extraction area

Historically, the type of mining possible in a gypsum deposit was either opencast or underground, depending mainly on the location of the stone, more or less close to the surface of the ground, and above all on the means of extraction available. 

In these open-cast mines, work was carried out exclusively on the surface, which is why the workings were commonly known as quarries. This was and is the most common type of mining for gypsum because it consists of exploiting outcrops that can be dismantled superficially, from top to bottom, digging and clearing until a vein, or “tetón” in the jargon of the gypsum workers, is found, creating terraces or vertical walls that can be accessed by lifting methods, regardless of the extraction method used.  In both cases, the quarry worker had to climb to the top of the quarry face and in others to hang on ropes for several metres, fixed to the quarry face.

In underground mines, which communicated with natural caves of great speleological value, excavations in the form of tunnels or galleries were necessary in order to extract the ore. Their exploitation entailed a greater risk, but also a higher cost. In the past, with the mechanical means available, trapezoidal pillars had to be built to support the roof of the mine, and if part of it was on loose ground, it had to be fortified by forming vaults with the same stone that was dismantled. This type of exploitation normally consisted of two mine entrances, one for the entrance to the extraction galleries and the other to allow the ore to exit through a loading dock, although in this quarry it was possible to find only one. 

They were extracted by hand. This type of extraction is the simplest and most arduous of all and was possible thanks to the low hardness of the gypsum and the structure in sheets or sheets of exfoliation that this natural variety, known as espejuelo gypsum, possessed.

With this method, gypsum was extracted at a shallow depth with the sole aid of picks, pickaxes, iron or wooden wedges, bars, hoists, augers, etc. After removing the topsoil and once the level of quality gypsum had been reached, holes were made to separate the pieces of rock using ‘prepalos’ or augers (an elongated iron bar, between 1.5 and 3 metres long, with one of the two ends shaped like a double bevel to perforate the rock) and with the help of a little water to soften the rock where the wedges were inserted. The wedges were placed equidistant from each other, drawing the outline of the stone to be extracted, and when they were driven in with the tapping of a mallet, the natural cracks that appeared allowed the material to come out.

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