Status: Available for Option


The target at Guadalcazar is an oxidized, precious metal-bearing polymetallic skarn deposit.

Location and Setting

The Guadalcazar project is located in central Mexico, approximately 85 kilometers northeast of the city of San Luis Potosí.

Land Status

The property consists of three claims totaling 182 hectares. Millrock owns a 100% interest subject to royalties payable to the Servico Geologica Mexicano (“SGM”).

Previous Exploration

Surface sampling, stream sediment/soil geochemistry and 1,220 m of diamond drilling in eight holes have been completed on the Dolores and Calaminas claims. Minor, poorly documented drilling and geophysics by the SGM in the 1980’s has been reported. Very limited surface sampling has been completed on the San Diego claim.

Geology and Mineralization

Cretaceous limestone and minor interbedded calcareous mudstone are intruded by a coarse grained, quartz -potassium feldspar phyric stock. The southwestern and western margins of the stock host oxidized and mineralized garnet-diopside-bearing skarns in addition to structurally controlled mineralization. The main porphyry-limestone contact hosts the largest mineralized bodies identified to date.

Historical mines on the project exploited precious and base metal-bearing (Au, Ag, Zn), iron oxide-rich skarn bodies exposed on surface. Structural zones extend from the contact into the intrusive body where endoskarn and minor sulfide-rich quartz veining host silver mineralization on the Dolores claim and further north on adjoining ground. On the Calaminas claim, well-developed oxide mineralization occurs along a dip slope of carbonate rocks and along the porphyry-limestone contact. Semi-continuous chip sampling (55 samples) along a strike of 220 m and across widths of 5-50 m in areas of mineralization yielded average grades of 0.25 gpt Au and 126 gpt Ag while 75 samples across 250 m of the northern zone averaged 0.69 gpt Au and 109 gpt Ag. Strong zinc mineralization is also present on surface, largely on the Dolores claim although the SGM reported underground sampling of 15.5 m @ 33% Zn on the Calaminas claim and drilling in 2013 intersected up to 27 m of 5.7% Zn.

Numerous small workings host zinc oxide occurrences within recrystallized limestone in the western half of the Dolores claim and on the Calaminas claim, south of the intrusive contact. These workings exploit manto and chimney replacement deposits peripheral to the main intrusive / limestone contact zones. Sampling by the SGM and Paget Southern Resources a company bought in 2014 Millrock and now named Recursos Millrock, returned high zinc and locally high silver grades over restricted widths and strike lengths.

Eight holes were drilled in 2013 on five sections along 600 m of the main mineralized trend. The drilling successfully intersected wide intervals of locally precious metal-bearing, massive, iron-oxide mineralization to a depth of 120 m below surface. Mineralized intercepts include high grade silver over significant intervals (22 m @ 148 gpt Ag) as well as wider lower grade intervals (108 m @ 65 gpt Ag) all as oxide*. The mineralized zone dips steeply to the north and will extend off the Millrock claim at depth. The contact oxide zone also hosts strong zinc mineralization including intervals of 27 m @ 5.7% Zn in GD‐07 and 12 m @ 7.8% Zn in GD‐04.


An option on the adjacent claims should be pursued and if successful further drilling to test the down-dip extension of the skarn system is recommended. Only the southern, best exposed part of the mineralized trend has been tested to date and drilling is recommended to test the northern part of the contact on the Dolores claim, as well as the contact area and the NE-dipping mineralized panel on the same sections as holes 1, 2 and 3. Further exploration is also warranted in the area of manto / chimney replacement mineralization, seeking larger oxide zinc bodies and underlying skarns at depth.

Continued dialog with local communities at Guadalcazar is vital in advancing further exploration programs. Though the community of Aguaje del Garcia favorably received the drill project employment and environmental controls, ongoing community relations will be required to maintain access to the project as well as gain access to the San Diego claim, located within the Abrego community.

Agreement and Terms

Millrock has made all pending payments and now owns 100% of the Guadalcazar claims, subject to a sliding NSR. Millrock is currently seeking potential joint venture partners for the Guadalcazar Project. If desired, Millrock can serve as operator on behalf of an earn-in partner.

Notes (*)

The reported 2013 drill intercepts are from an exploration program conducted by Pembrook Mining. Millrock’s Qualified Person has viewed the drill core but has not examined or verified assay certificates, grade calculations or QAQC/check sample results. The drill interval reported by Pembrook is interpreted to be close to true width.