I recommend you to start with data changes analisys. You can calculate correlation between Acct changes and each of commodities changes:
[TABLE="class: grid, width: 465"]
<colgroup><col><col span="6"></colgroup><tbody>[TR]
[TD]Date[/TD]
[TD]Acct[/TD]
[TD]Com1[/TD]
[TD]Com2[/TD]
[TD]Com1 Change[/TD]
[TD]Com2 Change[/TD]
[TD]Acct Change[/TD]
[/TR]
[TR]
[TD="align: right"]01.01.2014[/TD]
[TD="align: right"]65000[/TD]
[TD="align: right"]1194[/TD]
[TD="align: right"]19,81[/TD]
[TD] [/TD]
[TD] [/TD]
[TD] [/TD]
[/TR]
[TR]
[TD="align: right"]17.02.2014[/TD]
[TD="align: right"]73253[/TD]
[TD="align: right"]1330[/TD]
[TD="align: right"]21,94[/TD]
[TD="align: right"]11,4%[/TD]
[TD="align: right"]10,8%[/TD]
[TD="align: right"]12,7%[/TD]
[/TR]
[TR]
[TD="align: right"]19.02.2014[/TD]
[TD="align: right"]74148[/TD]
[TD="align: right"]1322[/TD]
[TD="align: right"]22,06[/TD]
[TD="align: right"]-0,6%[/TD]
[TD="align: right"]0,5%[/TD]
[TD="align: right"]1,2%[/TD]
[/TR]
[TR]
[TD="align: right"]23.02.2014[/TD]
[TD="align: right"]73492[/TD]
[TD="align: right"]1327[/TD]
[TD="align: right"]21,95[/TD]
[TD="align: right"]0,4%[/TD]
[TD="align: right"]-0,5%[/TD]
[TD="align: right"]-0,9%[/TD]
[/TR]
[TR]
[TD="align: right"]09.03.2014[/TD]
[TD="align: right"]70045[/TD]
[TD="align: right"]1339[/TD]
[TD="align: right"]20,89[/TD]
[TD="align: right"]0,9%[/TD]
[TD="align: right"]-4,8%[/TD]
[TD="align: right"]-4,7%[/TD]
[/TR]
[TR]
[TD="align: right"]13.03.2014[/TD]
[TD="align: right"]70752[/TD]
[TD="align: right"]1367[/TD]
[TD="align: right"]21,32[/TD]
[TD="align: right"]2,1%[/TD]
[TD="align: right"]2,1%[/TD]
[TD="align: right"]1,0%[/TD]
[/TR]
[TR]
[TD="align: right"]30.03.2014[/TD]
[TD="align: right"]62198[/TD]
[TD="align: right"]1294[/TD]
[TD="align: right"]19,82[/TD]
[TD="align: right"]-5,3%[/TD]
[TD="align: right"]-7,0%[/TD]
[TD="align: right"]-12,1%[/TD]
[/TR]
[TR]
[TD="align: right"]05.04.2014[/TD]
[TD="align: right"]62724[/TD]
[TD="align: right"]1302[/TD]
[TD="align: right"]19,96[/TD]
[TD="align: right"]0,6%[/TD]
[TD="align: right"]0,7%[/TD]
[TD="align: right"]0,8%[/TD]
[/TR]
[TR]
[TD="align: right"]12.04.2014[/TD]
[TD="align: right"]61738[/TD]
[TD="align: right"]1318[/TD]
[TD="align: right"]19,96[/TD]
[TD="align: right"]1,2%[/TD]
[TD="align: right"]0,0%[/TD]
[TD="align: right"]-1,6%[/TD]
[/TR]
[TR]
[TD="align: right"]08.04.2014[/TD]
[TD="align: right"]63023[/TD]
[TD="align: right"]1309[/TD]
[TD="align: right"]20,06[/TD]
[TD="align: right"]-0,7%[/TD]
[TD="align: right"]0,5%[/TD]
[TD="align: right"]2,1%[/TD]
[/TR]
[TR]
[TD="align: right"]11.06.2014[/TD]
[TD="align: right"]60825[/TD]
[TD="align: right"]1263[/TD]
[TD="align: right"]19,27[/TD]
[TD="align: right"]-3,5%[/TD]
[TD="align: right"]-3,9%[/TD]
[TD="align: right"]-3,5%[/TD]
[/TR]
[TR]
[TD="align: right"]27.06.2014[/TD]
[TD="align: right"]70594[/TD]
[TD="align: right"]1318[/TD]
[TD="align: right"]21,03[/TD]
[TD="align: right"]4,4%[/TD]
[TD="align: right"]9,1%[/TD]
[TD="align: right"]16,1%[/TD]
[/TR]
[TR]
[TD="align: right"]30.06.2014[/TD]
[TD="align: right"]71891[/TD]
[TD="align: right"]1328[/TD]
[TD="align: right"]21,06[/TD]
[TD="align: right"]0,8%[/TD]
[TD="align: right"]0,1%[/TD]
[TD="align: right"]1,8%[/TD]
[/TR]
[TR]
[TD="align: right"]07.07.2014[/TD]
[TD="align: right"]70519[/TD]
[TD="align: right"]1320[/TD]
[TD="align: right"]21,05[/TD]
[TD="align: right"]-0,6%[/TD]
[TD="align: right"]0,0%[/TD]
[TD="align: right"]-1,9%[/TD]
[/TR]
[TR]
[TD="align: right"]09.07.2014[/TD]
[TD="align: right"]73888[/TD]
[TD="align: right"]1326[/TD]
[TD="align: right"]21,1[/TD]
[TD="align: right"]0,5%[/TD]
[TD="align: right"]0,2%[/TD]
[TD="align: right"]4,8%[/TD]
[/TR]
[TR]
[TD="align: right"]10.07.2014[/TD]
[TD="align: right"]72968[/TD]
[TD="align: right"]1335[/TD]
[TD="align: right"]21,42[/TD]
[TD="align: right"]0,7%[/TD]
[TD="align: right"]1,5%[/TD]
[TD="align: right"]-1,2%[/TD]
[/TR]
[TR]
[TD="align: right"]12.07.2014[/TD]
[TD="align: right"]74865[/TD]
[TD="align: right"]1339[/TD]
[TD="align: right"]21,45[/TD]
[TD="align: right"]0,3%[/TD]
[TD="align: right"]0,1%[/TD]
[TD="align: right"]2,6%[/TD]
[/TR]
[TR]
[TD="align: right"]10.08.2014[/TD]
[TD="align: right"]73021[/TD]
[TD="align: right"]1309[/TD]
[TD="align: right"]19,91[/TD]
[TD="align: right"]-2,2%[/TD]
[TD="align: right"]-7,2%[/TD]
[TD="align: right"]-2,5%[/TD]
[/TR]
[TR]
[TD="align: right"]17.08.2014[/TD]
[TD="align: right"]71425[/TD]
[TD="align: right"]1304[/TD]
[TD="align: right"]19,55[/TD]
[TD="align: right"]-0,4%[/TD]
[TD="align: right"]-1,8%[/TD]
[TD="align: right"]-2,2%[/TD]
[/TR]
[TR]
[TD="align: right"]13.09.2014[/TD]
[TD="align: right"]64673[/TD]
[TD="align: right"]1129[/TD]
[TD="align: right"]18,61[/TD]
[TD="align: right"]-13,4%[/TD]
[TD="align: right"]-4,8%[/TD]
[TD="align: right"]-9,5%[/TD]
[/TR]
[TR]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[TD]Com1 to Acct corelation:[/TD]
[TD]Com2 to Acct corelation:[/TD]
[TD][/TD]
[/TR]
[TR]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[TD="align: right"]79,1%[/TD]
[TD="align: right"]90,4%[/TD]
[TD][/TD]
[/TR]
</tbody>[/TABLE]
It shows you that Com2 price is more linked to Account price than Com1 price.
Then, based on other data (f.e., actual mix of metals in your mines), you can perform other analisys.
Hope it can helps for start