Notes on the extraction of Classic Grey Montemerlo Trachyte
Modern methods use "pit" mining, and the current quarry yard lies a few dozen meters below the level of the countryside. Cracking phenomena characterize the quarry front, and this is how large, quadrilateral prism sections are identified. Their natural weak slope is exploited during the initial mining phase, with the help of small explosive charges. The next phase of production, also conducted on site, consists in reducing the large masses into more or less square blocks. This operation, assisted by trachyte's tendency to cleave along straight, uniform lines, is accomplished by tapping with metallic props in the direction desired. The squared blocks then move on to the workshop, where they are worked into the shapes and sizes desired, using circular saws and diamond milling cutters.
Additional information from the web
Read on Wikipedia about Trachyte.
