One of the wines produced by the local Pinoso Bodega is named for the hill, it's called Diapiro and diapiro is the Spanish equivalent of the technical word, diapir in English, to describe the geological phenomenon where the light, and plastic, salt has been squeezed up through the harder, surrounding rock.
The salt in Monte Cabeço has been mined for years, at least since Roman times. The hill is basically millions and millions of tons of Triassic salt. Salt in its mineral form is called halite. In the past the salt was mined by digging it out with picks and shovels but nowadays the salt is extracted by drilling a borehole, injecting pressurised water into the rock to dissolve the salt and then pumping out the resultant brine. The saltwater solution is sent down a 53 km gravity fed pipeline to Torrevieja. There the solution is added to the salt lagoons, already partially filled with salty water from the Mediterranean. The Pinoso brine increases the concentration of salt in the water so, as the hot sun evaporates the water from the shallow lagoons, it leaves behind tons and tons, 550,000 last year, of salt ready for the chemical industry, for road gritting, for any number of industrial uses and even to add a bit of taste to your food despite what the doctor told you.