Dunno about now, but p.126 of The Compendium of American Railroad Frequencies, Kalmbach Publ., 1993, shows BSR as 47.48 for quarry switching. Low Band is uncommon for rr ops, so guessing that is/mebbe was the quarry's general frequency. Also guessing it might be low wattage, so not much carry.
"A gray crossover is definitely not company transportation."