The Chester vein has been the major source of ore from the Sunshine mine, largest single producer of silver in the world. 425 samples of quartzite and argillite wall rocks were collected in 13 traverses across this vein on the 4400, 4600, and 4800 mining levels. These samples were analyzed for aluminum, magnesium, calcium, sodium, potassium, manganese, iron, lead, copper, and zinc by atomic absorption spectroscopy, and for silicon and sulfur by x-ray emission spectroscopy. Element distribution plots, linear correlation coefficient matrices, varimax factor analysis, and cluster analysis were employed to determine the geochemical processes that occurred in the wall rock.
Examination of element distributions established that large scale leaching of calcium occurred concurrently with a stage of bleaching in the wall rock. Subsequent to this bleaching process, carbonatization (sideritization) of the wall rock, which occurred during siderite emplacement in the vein, resulted in aureoles of iron, manganese, magnesium, and calcium in the wall rock near the vein. These aureoles were shown to increase the exploration target by a factor of about 10.
An inverse relationship was statistically established between sericite, represented by aluminum and potassium, and siderite, represented by iron and manganese, in the wall rock. The cause of this relationship was not determinable. It is recommended that a mineralogical study supercede this study to resolve this problem.
The technique of cluster analysis was modified in order to permit meaningful geochemical interpretations. The modified technique provided the same results as factor analysis, but offered the advantage of an easily understood graphical representation of results --Abstract, page ii
