San Albino Gold Deposit
Property2009/2010 Exploration Results (San Albino)
During the period from October 2009 to the end of 2010, the Company completed reconnaissance level exploration across the entire Property, with a focus on the southern (San Albino) district and the northern (Murra) district.
In the San Albino District, the Company completed a core drilling program, totaling 1,514.75 metres, over the San Albino Mine and Arras prospects. Drilling confirmed the thickness, grade and continuity of the San Albino Mine mineralization.
The primary objectives of the 2010 drill exploration program were to (1) confirm and evaluate the size and grade of known mineralized zones within the San Albino Mine area and (2) test the lateral and down-dip extension of the San Albino vein mineralization. The historical San Albino Mine area contains two primary mineralized zones some 450 metres apart - the San Albino zone and the Arras/San Lorenzo zone.
A fence of nine drill holes was drilled at five sites, approximately 25 to 50 metres apart. Except for drill hole SA10-01, two holes were drilled from each drill pad; one was angled between 45 to 55 degrees and the other between 70 to 90 degrees.
The gold bearing structures strike northeast-southwest (60o) and consist of quartz veins containing small amounts of galena, pyrite, sphalerite, arsenopyrite and native gold. The quartz veins lie within graphite flooded shear zones. The hanging and footwall sections of the vein consist of mineralized quartz veinlets within the graphite altered fault gouge.
The San Albino vein lies within a large shear zone of phyllites and schists. The sheared rocks are quite porous and amenable to the emplacement of gold by mineralizing fluids; thus, mineralization is often found in both the quartz vein and country rock adjacent to the vein. The Company sampled and assayed the entire length of each drill hole; however, only mineralized intervals are reported in this news release.
Historical data from the San Albino Mine was compiled and used to locate the position and orientation of the San Albino vein. Drill hole SA10-01 was designed to intersect the 400 level of the San Albino Mine in order to confirm the location of the drift and determine the elevation of the adit. The adit was intersected at a depth of 29.0 metres, where most of the vein appears to be mined out; however, significant mineralized intervals were still intersected (see table below).
Drill holes SA10-02 to SA10-05 each intersected the San Albino vein and extended the strike length
of the known vein to the southwest for an additional 62 metres, to approximately 200 metres. Drill hole SA10-04 identified a new, parallel mineralized zone
, approximately 86 metres below the San Albino zone.
Two holes, SA10-06 and SA10-09, were drilled to a depth of approximately 300 metres to test for additional mineralized structures situated parallel to the San Albino vein. Drill hole SA10-06 intersected a total of four highly mineralized gold zones
, ending at 284.38 metres within a graphitic schist package hosting gold mineralization. The San Albino zone was intersected at 48.2 metres. The three new parallel gold zones were intersected at 128.93 metres, 247.50 metres and 268.00 metres depth, respectively. Drill hole SA10-08 was stopped short at 43.22 metres depth due to very poor recovery; however, the San Albino vein (Zone 1) was intersected. Drill hole SA10-09, drilled from same location as SA10-08, reached a depth of 284.38 metres. It intersected the San Albino zone and a second, mineralized vein believed to be Zone 2, which was initially located by drill hole SA10-04.
A cross-section from San Albino drill hole SA10-06 to the Arras surface showing indicates that the Arras mineralized zone can be traced 450 metres down dip. The Arras zone, which has already been traced for 200 metres along strike, is open in both directions and down dip. The third intersection in drill hole SA10-06, which returned 4.0 metres of 13.67 g/t gold and 31.41 g/t silver
including 0.8 metres of 42.28 g/t gold and 123.0 g/t silver, and the Arras mineralization are not only visually similar but also chemically similar in that the silver to gold ratio is approximately 2:1. Additional drilling is required to conclusively determine if in fact Zone 3 intersected beneath San Albino Mine is the down-dip extension of the Arras vein.
San Albino Mine
The San Albino deposit is described as a thick lenticular quartz-pyrite vein several hundred feet long, with a general NW strike, and it dips about 40 degrees NE, parallel to the dip of the enclosing phyllites. Chalcopyrite is locally abundant in the lower mine levels and arsenopyrite is also said to increase downward.
The San Albino underground development consists of a 300L main drift, three x-cuts: 200L, 300L, and 400L, excavated at different locations in the NW side of the mineralized structure, and El Naranjo cross-cut developed in the south side of Cerro San Albino. All of these have been caved and it is the Company's intention to rehabilitate levels 300L and 400L.
Golden Reign is currently reviewing a wealth of historical documentation regarding the historic and forgotten San Albino Gold Mine, provided by the Huntington Library Historical Documents (Charles H. Janin Papers) and the University of Wyoming Heritage Centre (Thayer Lindsley Papers
). Within the collection of documents are original mine plans, letters and geological reports.
Regional and local geology have been well described by Condor (2009) and by Bengoechea (2009), from Western Mining (1996) which this summary has been compiled.
The San Albino-Murra Concession covers over 20 kilometers strike extent of a belt of Paleozoic metamorphic rocks within a structural trend known as the Guayape Suture Zone. The dominant rock type is metasedimentary phyllite and schist with subordinate massive pelite and possibly some sandy layers. In the areas of gold mineralization graphitic schist is extensively present. The metasediments are locally intruded by massive granite bodies and felsic to intermediate dykes, the most significant being a granite-quartz monzonite batholith that forms the Dipilto-Jalapa mountain range to the north of the project area. The granite-quartz monzonite has been isotopically dated as Upper Cretaceous.
Goeser (1996) states that the sequence of events within the metamorphic terrain is readily apparent. A first regional foliation and concordant quartz veins (S1) indicate an initial stage of compression. Recumbent folding of S1 structures may or may not indicate a subtle, second compression event, although there are no foliation or crenulations as yet seen to verify this. Vertical to sub-vertical normal faults, fractures, shear, and quartz veins are denoted S2. S2 structures severally disrupt and displace S1 foliation and quartz veins. A second extensional event, S3, has characteristics and sub-perpendicular to S2. S3 structures are possibly conjugates of S2. Judging from small-scale mines and the frequency of sulphide content of specific quartz veins, S1 veins seem to be primary carries of gold and silver mineralization hosted in the meta-sedimentary rocks in the northwestern region of Nicaragua.
Topographic trends indicate a dominant north-east striking foliation, interpreted as the axis of maximum compression in the suture zone. There is outcrop evidence of considerable structural thickening of the schist package, such as over thrusting and tight folding. Western Mining Corporation's geologists identified structures relating to compression and subsequent extension and suggested the following sequence of events (Monthly Exploration Report, Jan 1996):
- Compression (S1) forming regional penetrative foliation and concordant
- Continued or subsequent compression leading to recumbent folding of S1
- Extension (S2) forming vertical and sub-vertical normal faults,
fractures, shears, and quartz veins offsetting S1 structures.
- Conjugate set or second extensional event (S3?) forming near
perpendicular faults and fractures to S2 structures.
Mapping by Condor Resources has demonstrated variations in the direction of the structural components between the northern and southern parts of the concession area. When interpreting these variations it is suggested that there is a possible 400 meter net rise in structural position over a distance of 15 kilometers from the south-west (San-Albino block) to north-east (Murra block). Most of the mineralized veins in the south-western San Albino block and Potrerillos Concession appear to strike at 2400 (south-west) and dip towards the northeast, while mineralized structures at a higher altitude in the north-eastern Murra block are orientated either near horizontal, striking north-south or southeast.
The gold, silver, and sulphide-bearing quartz veins are interpreted as of probable late stage.
The volcanic rocks cropping out on the southern region of the concession represent isolated outcrops of the Tertiary volcanic rock that cover most of Nicaragua; and in the area lithologies consist of deeply weathered andesites and basalts.
The hydrothermal gold mineralization in the concession region occurs along a belt parallel to the contact zone of the intrusive with the host phylites, in quartz veins, quartz pods and lenses deposited in the phyllite, free gold stringers sometime fill the small quartz fractures. Free gold also have been observed disseminated in the phyllite. The mineralized vein structures generally consist of white quartz; thickness, strike length, and depth are controlled by the hosted phyllite structural conditions.