The San Celso property consists of three contiguous mining concessions located 50 km southeast of Zacatecas, the regional capital. The project hosts two historic underground silver mines, the San Celso and the Las Cristinitas mines. Records refer to initial mining taking place in early colonial times on the San Celso mine itself, and that it was developed to at least 130m depth from surface on at least three levels. There are no historic production records for the mine however its know that exceptional high grade ore was mined.
The San Celso and Las Cristinitas veins occurs on the east side of a prominent hill called El Morro. The hill is a rhyolite plug, which is thought to be younger than the mineralisation at San Celso since mineralisation appears to be cut by the plug. The wallrock at San Celso is the intermediate intrusive of the Panﬁlo Natera batholith.
The Las Cristinitas vein is located in the footwall of the San Celso vein, approximately 115m to the east-northeast. Early sampling in 2006 indicates that it is similar if not higher grade tahn the San Celso vein. The width of the Las Cristinitas structure appears to be greater than that of the San Celso vein since mineralisation occurs in both the footwall and hanging wall as well as the vein itself.
In 2006 a detailed underground mapping and sampling program was carried out in both mines. A total of 438 samples from the San Celso and Las Cristinitas workings and dumps were collected. Of these 265 chip-channel samples were from the Las Cristinitas workings. Assay results included a 4.65m interval at >1000 g/t Ag including 1.05m at 2,683 g/t Ag, 78.2 oz/t Ag.
Historic underground geological mapping also identified further mineralisation comprising a 6m wide structure between the Las Cristinitas Vein and the San Celso Vein. This vein structure is approximately 10-20m in the footwall of the San Celso vein. It is thought that this may be the strike extension of the Nueva Andromeda vein which has been historically mined just outside the current Alien tenement boundary.
At San Celso, the geologic setting, high silver content and characteristic vein mineralogy and textures confirm the affinity of this system with other deposits of this style in Zacatecas and elsewhere in Mexico such as Fresnillo, San Martín de Bolaños, Guanajuato and Pachuca-Real de Monte.
Gold and silver grades in low-sulfidation epithermal systems as present at San Celso can be very high, occasionally reaching gold grades in the order of tens of grams of gold per tonne and kilograms of silver per tonne, as is seen in the historic sampling (see below) and the most recent round of sampling completed in July 2019 by Alien Metals.
The mineralised samples to date suggest that the historic miners only removed and processed the exceptionally high grade/bonanza grade ore, both due to ease of extraction of the silver and to minimise the amount of material they had to mine.
Further to a site visit in early 2020 and discussions with the companies experienced Mexican technical team it is apparent that San Celso offers great potential to contain an economic silver resource. Some ore grade material is present at surface in both historic mine dumps and in various adits.
Being at a slightly higher elevation than the surrounding area there appears to be little or no water in the old workings and, as these workings were sampled and mapped in 2006, a provision to re-enter the workings to carry out updated sampling and mapping is currently being planned. Once this work is completed it would aid in finalising initial drill positions and add a lot of valuable information on the mineralisation grade, width and potential.
The next stage of work is a diamond core drilling program which is being designed to test the mineralised veins and systems to commence resource development. Current drill permitting is in progress as per the legal requirements in Mexico and Alien hope to have this completed by the end of Q2 2020.
There is a large skilled workforce with extensive underground mining experience in the region and in conjunction with Alien’s highy experienced in-country technical team the majority of work can be carried out in-house which will ensure excellent quality of work, great continuity of work and be cost effective.
- San Celso contains at least two historic silver mines
- Alien sampling has confirmed bonanza grade results up to 2,683g/t (78 oz/t Ag)
- Potential to develop a mineable resource
- Potential to expand land holding
- Historic waste and maybe ore dumps on surface remain to be tested for silver content.
|Deposit Style||Epithermal very high grade|
|Key Attributes||Very high grade epithermal mineralisation typical of the region|
|Asset Stage||Resource definition|
|Results||2683 g/t Ag (78 Oz/t), 1475 g/t Ag, 1209 g/t Ag|
|Next Phase of Work||Underground QA/QC sampling followed by drilling|
Bonanza Grade underground samples, San Celso Project, 2006
|ASSAY NUMBER||SAMPLE NUMBER||Ag (g/t)||Ag (Oz/t)|