La Escondida

Status: Available For Option


La Escondida is an Epizonal phase (Ag-Au-Sb) Orogenic target. This target is structurally controlled and characterized by both brittle faults and ductile shear zones. The property contains mineralized breccias and shear zones containing altered quartz veins and veinlets.  The orogenic system is overprinted by a younger low sulfidation epithermal system vein system containing Ag-Pb-Zn.

Location and Setting

The property is located in northern Sonora, 120 km northeast of Hermosillo near many gold and silver deposits some of the most important of which are El Chanate, San Francisco and Santa Elena.

Land Status

The mining concessions total 178 has and include La Escondida (T-23052) with 25 Ha and La Escondida (T-230499) with 153 Has.

Previous Exploration

Various historic mine workings exist along and within the mineralized structures, including mine shafts and mine tailings. Alió (Timmins Gold) and VVC Corp. previously conducted exploration including geochemical sampling and geologic mapping. To Millrock’s knowledge no drilling has ever been conducted.

Geology and Mineralization

A strongly deformed (compressed) Jurassic age volcano-sedimentary sequence consisting of alternating clay, siltstone, sandstone, andesite sills and lenses of limestone is intruded by Ag bearing monzonite and diorite stocks. The general trend of the volcano sedimentary sequence is 250° to 265° dipping to the north. This package of rocks is cut by at least three structures-oriented east - west and dip south in the opposite direction to the bedding of the volcano-sedimentary sequence. The structures are subparallel and closely spaced with no more than 100 meters separation between them. These structures are 1.5 to 3 meters wide and have a strike length of 250 to 800 meters within the mining claim area.  Historic samples and recent sampling by Millrock has confirmed high Ag grades (more than 750 ppm) over the mineralized structures and more than 1,800 ppm Ag in historic workings. Associated gold values are as high as 1.8 ppm Au.

Argillic and sericitic alteration is associated with the sediments and andesite sills which contain 1-2% disseminated, oxidized, sulfides. Quartz and calcite veins and veinlets form local zones of stockwork and associated alteration. Large structures contain are surrounded by alteration halos up to 20 meters wide.

A monzonite stock located in the central part of the property contains argillic and sericitic alteration with quartz and calcite veinlets.  A sample from this outcrop returned 30 ppm Ag which suggests a low grade disseminated deposit could exist at depth.


Recommendations include: Semi-detailed geologic mapping with rock sampling over the entire property to define structural controls and alteration associated with the Ag-Au mineralization;  Continuous rock sampling perpendicular to the structures to define mineralized bodies on the surface; soil sampling to define anomalies in Ag, Au, Sb and As; Ground magnetic susceptibility survey to define high and low magnetic anomalies to delineate possible intrusive bodies at depth; dipole-dipole induced polarization geophysical surveys lines to better define structural controls and dips of structures.

Agreement and Terms

Millrock has 100% control of the property through an option to purchase agreement with private owners. There is no NSR.