▁Horn os ▁del ▁Mediter rá neo ▁S . A ., ▁ceased ▁their ▁activity ▁in ▁ 1 9 8 4 ▁and ▁the ▁Sierra ▁M ener a ▁min ing ▁company ▁went ▁bank rupt ▁in ▁ 1 9 8 7 , ▁following ▁which ▁the ▁mines ▁and ▁their ▁subs idi ary ▁facilities ▁were ▁closed . ▁Mass ive ▁un emp loyment ▁hit ▁the ▁min ing ▁town ▁of ▁O jos ▁Neg ros ▁after ▁min ing ▁activity ▁in ▁the ▁nearby ▁mountains ▁ceased . ▁As ▁a ▁consequence ▁its ▁population ▁went ▁from ▁ 3 0 0 0 ▁in ▁the ▁ 2 0 th ▁century ▁to ▁ 5 6 0 ▁in ▁ 2 0 1 0 . ▁ ▁At ▁the ▁time ▁of ▁the ▁closure ▁of ▁the ▁mines ▁there ▁was ▁no ▁official ▁reg ulation ▁forcing ▁the ▁min ing ▁company ▁to ▁repair ▁the ▁environmental ▁damage ▁caused ▁by ▁its ▁activity . ▁The ▁Spanish ▁M ining ▁Law ▁relevant ▁at ▁the ▁time ▁didn ' t ▁include ▁a ▁provision ▁regarding ▁environmental ▁impact ▁of ▁min ing ▁activity ▁when ▁it ▁was ▁prom ul g ated ▁in ▁ 1 9 7 3 . ▁ ▁See ▁also ▁▁ ▁Mountains ▁of ▁Arag on ▁ ▁O jos ▁Neg ros ▁ ▁References ▁ ▁External ▁links ▁▁ ▁R ama ▁a rag ones a ▁del ▁S istema ▁Ib ér ico ▁ ▁Lag una ▁de ▁Al m oh aja ▁ ▁S ag unto ▁Ant igu as ▁min as ▁de ▁O jos ▁Neg ros ▁ ▁V ía ▁Ver de ▁de ▁O jos ▁Neg ros ▁▁ ▁M ener a ▁M ener a ▁M ener a ▁Category : M ining ▁in ▁Spain