Rubble stone — sang-e lashe — is stone that cannot be used as a dimension or facing stone, but is sound enough to be used for producing sand and gravel, building walls, in bridge foundations, and as railway ballast. Quarries that do not yield block or cut stone are worked as rubble-stone quarries.
Where it is used
Ordinary building stones used as rough or hammer-dressed stone, or in irregular shapes, for building foundations, walls and bridge piers fall in the rubble-stone class. Rubble is also the feed from which stone powder is produced in stone-crushing plants.
Rubble at Nangerd
The Nangerd permit is issued for rubble stone (andesite). Part of the extracted stone is sound rough stone for riprap, walls and foundations; the rest is fed to the crushing lines and turned into ballast, sand and gravel. Because the deposit is heavily jointed, it is worked with ripper and breaker rather than heavy blasting, which keeps the stone sound and the fines low.
