$SHVLF High grade mineralization was discovered at

$SHVLF High grade mineralization was discovered at San Martin in the 18th Century, and is reported to have been mined over a period of 40 years; however, no production records exist. Between 1900 and 1924, an estimated 250,000 tonnes grading 15 g Au/t and 100 g Ag/t was reportedly mined. Mineralization occurs in Upper Cretaceous black limestone and calcareous shales of the Soyatal Mexcala Formation as electrum, and silver selenide minerals principally associated with quartz and to a lesser degree with calcite. The deposit is an epithermal, probably high sulphidation precious metal (Ag-Au) type (metal ratio Au:Ag at 1:10), related to a Tertiary dacitic/andesitic intrusive dome.