["< sod > the'''blue mountain quarry'''( first introduced in'' [ [ blue mountain mystery ] ]'' ) is on a large cement slate quarry, located on approximately one of the narrow gauge lines of the skarloey railway. < eod > < sod > [UNK] the'''blue mountain quarry'''( first introduced in'' [ [ blue mountain mystery ] ]'' ) is a large concrete slate quarry, located on one of three the narrow gauge lines east of the skarloey branch railway. it is also served by a standard broad gauge branch line that breaches of the peel ferry godred line. < eod >"]