A total of 16 principal low sulphidation epithermal vein/stockwork/breccia zones, have been identified on the Mercedes property. The currently producing veins have been divided into three sub-district areas:
• Mercedes Area (Mercedes-Barrancas).
• Klondike Area (Klondike/Rey de Oro)
• La Lupita Area (Lupita-Diluvio)

The mineralized zones display a combination of fissure vein, stockwork, and breccia morphologies that change rapidly on strike and dip. The zones range in width from less than 1.0 m to composite vein/stockwork/breccia zones up to 15.0 m wide. In the Diluvio zone, goldsilver-bearing vein/stockwork zones local attain thicknesses in excess of 100.0 m. Length of individual veins varies from 100 m to over 2.0 km. Property-wide, Au-Ag bearing veins occur over a vertical range greater than 600 m (680 m to 1,300 m).

Metallurgical studies have identified the presence of very small quantities of native gold, native silver, electrum, pyrargyrite, stibnite, galena, sphalerite and chalcopyrite in heavy mineral concentrates. Copper minerals such as malachite and chrysocolla are most common as fracture fillings in breccias at Klondike, but rare specks are also seen in the Mercedes and Lupita-Diluvio veins.

The Mercedes Mine is a mechanized decline access underground mine with three separate underground mines (Mercedes, Klondike, and Lagunas Barrancas).

The planned production rate is approximately 2,000 tpd to 2,100 tpd. Ore from underground is hauled by dump truck to stockpiles near the portal. Ore from the Barrancas and Klondike mines (and from Diluvio in future) is hauled to a common stockpile area near the jaw crusher.

There are two underground mining methods in use at Mercedes. Where the rock quality is appropriate, the ore is mined by long hole open stoping with cemented paste backfill. This is expected to be applied to 70% of the deposit. For areas with poorer rock conditions, the mining method is mechanized cut and fill stoping.

The process is based on conventional milling with Merrill Crowe recovery using the following unit processes.
• Three-stage crushing with closed circuit tertiary
• Mill in closed circuit with cyclone classifiers
• Gravity concentration
• Agitated leach
• Counter current decantation
• Merrill Crowe precipitation
• Smelting
• Tailings detoxification
• Tailings disposal