Alabaster occurs among sedimentary rocks formed in basins where evaporation has been significant, which has led to salts accumulation (evaporite basins). Series with plenty of gypsum are looked for, and the possible existence and likely location of alabaster beds are assessed.
After checking in situ by field survey and sampling and, when appropriate, pit opening, mining possibilities are assessed by considering topography, waste rock volume, mineral deposit richness, accessibility and mineral price on the market.
When the interest of the site is determined, the extraction of alabaster stone is performed by carrying out the following tasks:
1. The removal of the covering materials until the alabaster is reached can be performed:
Down the hill
Down the slope
Digging up a trench
2. Simultaneously to the excavation the waste materials extracted are used in the construction of high, medium-degree sloped or filled embankments.
3. Preparation of the esplanade or work platform at a level suitable for placing mining machinery.
4. Extraction and staking of the bolulders.
5. Husking by using pneumatic chipping hammers. Between 30% and 75% of material is lost in this operation depending on the alabaster stone type, quarry features, the hammer used and the labourer. The final destination of the waste matter is the local landfill.
6. Transportation of the boulders to the sawmill.
7. Restoration of the site, which can be developed simultaneously to the mining in those areas already exploited and in finished embankments. The final goal is to leave the site in a condition that strongly resembles the original one, or at least a condition that does not alter the original landscape significantly.
In Aragon there are many sites that have become degraded as a consequence of alabaster mining. Both extraction following the contour mining method, which extends over hills and slopes, and the wide dispersion of active and abandoned exploitations that have not been restored, or have been very poorly restored, have resulted in serious environmental damage, which has affected large areas.
Much of the world’s alabaster stone extraction is performed in the centre of the Ebro Valley. Elsewhere, it has either been depleted, or its extraction is so difficult that it has almost been abandoned or is carried out at a very high cost. In Spain, alabaster has been extracted in various places, although these days extraction remains only at the sites in Aragon.
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