ø g ger ▁named ▁this ▁min eral ▁dah ll ite ▁after ▁T elle f ▁D ah ll ▁and ▁his ▁brother ▁Johan ▁who ▁ran ▁min ing ▁operations ▁there ▁at ▁the ▁time . ▁ ▁History ▁In ▁the ▁mid - 1 8 0 0 s , ▁it ▁was ▁discovered ▁that ▁ph osph orus , ▁an ▁essential ▁nut ri ent ▁that ▁many ▁cro ps ▁lack ed , ▁could ▁be ▁used ▁more ▁effectively ▁in ▁fert il izer ▁if ▁sul fur ic ▁acid ▁was ▁added ▁to ▁ph osph ate ▁rocks , ▁creating ▁super ph osph ate ▁in ▁the ▁process . ▁ ▁Al most ▁immediately ▁ph osph ate ▁min er als ▁such ▁as ▁ap at ite ▁were ▁in ▁high ▁demand , ▁and ▁it ▁was ▁discovered ▁that ▁the ▁ap at ite ▁found ▁in ▁B am ble ▁was ▁especially ▁light ▁in ▁color , ▁indicating ▁a ▁high ▁concentration ▁of ▁ph osph ate . ▁ ▁A pat ite ▁samples ▁taken ▁from ▁the ▁mines ▁were ▁described ▁as ▁course , ▁hard ▁l umps ▁with ▁a ▁white ▁yellow ish ▁color ▁and ▁an ▁average ▁of ▁ 8 5 % ▁ph osph ate ▁content . ▁ ▁The ▁mines ▁now ▁known ▁as ▁ Ø deg år den ▁Ver k ▁started ▁as ▁two ▁separate ▁operations : ▁the ▁ Ø st gru ven ▁and ▁the ▁V est gru ven , ▁or ▁D ah ll s ▁field , ▁mines . ▁The ▁ Ø st gru ven ▁operation ▁was ▁started ▁in ▁ 1 8 7 2 ▁by ▁Comp ag nie ▁Fran çaise ▁des ▁M ines ▁de ▁B am ble , ▁a ▁French ▁min ing