▁area ▁was ▁ref ined , ▁but ▁silver ▁could ▁not ▁be ▁reli ably ▁recovered . ▁ ▁Fair field ▁wrote ▁that ▁the ▁mill s ▁were ▁processing ▁ore ▁from ▁the ▁Com stock ▁L ode , ▁which ▁was ▁being ▁released ▁by ▁the ▁alk ali ▁dust ▁in ▁the ▁Black ▁Rock ▁ore . ▁ ▁This ▁would ▁account ▁for ▁the ▁fact ▁that ▁the ▁first ▁run ▁of ▁Black ▁Rock ▁ore ▁would ▁result ▁in ▁high ▁values , ▁but ▁later ▁runs ▁would ▁have ▁low ▁values . ▁ ▁The ▁Hard in ▁City ▁area ▁never ▁produced ▁significant ▁quantities ▁of ▁silver , ▁though ▁Lad ue ▁V ary ▁came ▁to ▁Hard in ▁City ▁to ▁prospect ▁and ▁in ▁ 1 8 8 4 ▁found ▁silver ▁and ▁gold ▁to ▁the ▁n ortheast . ▁ ▁In ▁ 1 9 0 9 , ▁a ▁spec imen ▁of ▁ore ▁similar ▁to ▁the ▁ore ▁found ▁by ▁Hard in ▁was ▁discovered ▁at ▁Hard in ▁City ▁in ▁a ▁p ile ▁of ▁ore ▁left ▁by ▁previous ▁prospect ors . ▁ ▁V ander burg ▁states ▁that ▁Hard in ' s ▁silver ▁was ▁probably ▁from ▁the ▁Silver ▁Cam el ▁mine ▁near ▁Sul ph ur , ▁Nev ada . ▁The ▁Silver ▁Cam el ▁Mine ▁has ▁cer arg y rite ▁also ▁known ▁as ▁ch lor arg y rite ▁or ▁horn ▁silver . ▁ ▁Cer arg y ite ▁is ▁silver ▁ch lor ide ▁( Ag Cl ), ▁which ▁does ▁not ▁match ▁the ▁carbon ate ▁of ▁silver ▁and ▁lead ▁as ▁reported ▁by ▁Fair field ▁above . ▁ ▁References ▁ ▁Further ▁reading ▁▁ ▁" The ▁Black ▁Rock ▁Silver ▁M ines ," ▁San ▁Francisco