copper

58:7.6This stone layer, the old­est fos­sil-bear­ing stra­tum in the crust of the earth, has been crum­pled, folded, and grotesquely twisted as a re­sult of the up­heavals of earth­quakes and the early vol­ca­noes. The lava flows of this age brought much iron, cop­per, and lead up near the plan­e­tary sur­face.

65:6.4One of the most ser­vice­able and com­plex episodes in the evo­lu­tion of the higher types of an­i­mals con­sisted in the de­vel­op­ment of the abil­ity of the iron in the cir­cu­lat­ing blood cells to per­form in the dou­ble role of oxy­gen car­rier and car­bon diox­ide re­mover. And this per­for­mance of the red blood cells il­lus­trates how evolv­ing or­gan­isms are able to adapt their func­tions to vary­ing or chang­ing en­vi­ron­ment. The higher an­i­mals, in­clud­ing man, oxy­genate their tis­sues by the ac­tion of the iron of the red blood cells, which car­ries oxy­gen to the liv­ing cells and just as ef­fi­ciently re­moves the car­bon diox­ide. But other met­als can be made to serve the same pur­pose. The cut­tle­fish em­ploys cop­per for this func­tion, and the sea squirt uti­lizes vana­dium.

58:7.10Some of the up­per lay­ers of these tran­si­tion rock de­posits con­tain small amounts of shale or slate of dark col­ors, in­di­cat­ing the pres­ence of or­ganic car­bon and tes­ti­fy­ing to the ex­is­tence of the an­ces­tors of those forms of plant life which over­ran the earth dur­ing the suc­ceed­ing Car­bonif­er­ous or coal age. Much of the cop­per in these rock lay­ers re­sults from wa­ter de­po­si­tion. Some is found in the cracks of the older rocks and is the con­cen­trate of the slug­gish swamp wa­ter of some an­cient shel­tered shore line. The iron mines of North Amer­ica and Eu­rope are lo­cated in de­posits and ex­tru­sions ly­ing partly in the older un­strat­i­fied rocks and partly in these later strat­i­fied rocks of the tran­si­tion pe­ri­ods of life for­ma­tion.

81:3.4The wide­spread use of met­als was a fea­ture of this era of the early in­dus­trial and trad­ing cities. You have al­ready found a bronze cul­ture in Tur­kes­tan dat­ing be­fore 9000 B.C., and the And­ites early learned to work in iron, gold, and cop­per, as well. But con­di­tions were very dif­fer­ent away from the more ad­vanced cen­ters of civ­i­liza­tion. There were no dis­tinct pe­ri­ods, such as the Stone, Bronze, and Iron Ages; all three ex­isted at the same time in dif­fer­ent lo­cal­i­ties.

81:3.5Gold was the first metal to be sought by man; it was easy to work and, at first, was used only as an or­na­ment. Cop­per was next em­ployed but not ex­ten­sively un­til it was ad­mixed with tin to make the harder bronze. The dis­cov­ery of mix­ing cop­per and tin to make bronze was made by one of the Ad­am­son­ites of Tur­kes­tan whose high­land cop­per mine hap­pened to be lo­cated along­side a tin de­posit.