Geology, Drilling And Sampling


At the Fujian Project, drilling has been ongoing for more than six months since it began. The team mostly drilled into the higher portions of the deposit with 62 diamond drill holes from the surface and 148 holes below (from the adits), sampling half-core only for gold. The drill core was only examined in the areas that were thought to contain at least some gold. None of the remaining core was sampled. The knowledge base in that area of the deposit is lacking due to the absence of sulfate and arsenic tests there. Surface reverse circulation (RC) drilling in the pit and horizontal drill holes within the adits have partially filled this in. The grade control drilling program will produce the Sulfur model in the future using blast holes that were drilled inside the open pit. 43km of drill holes were drilled at the Fujian Project and its surrounding area in 2016. Yazhou Huangjin had completed 253 drill holes totaling 78km of drilling in the Fujian Project as of the end of 2016.

Half-cores of the drill core are cut, collected, and analyzed for Au, As, S, Hg, and Sb. The majority of the drill core is NQ size (45.6mm in diameter, or around 62% of the total core taken). Additionally, cores of the HQ size (61.5mm diameter) and PQ size (75mm diameter) have been taken. Only the drill core pieces that were thought to have at least some gold in them were analyzed. At this time, the remainder of the core is not being analyzed.

To offer some grade control and further information on S and As for the initial open pit mining, Yazhou Huangjin has drilled a series of closely spaced, inclined Reverse Circulation (RC) holes (35m along strike by 35m down dip) within the shear zone at the surface. The grades and tons so far recovered from the closely spaced RC drilling and the blast hole samples in the top benches of the pit have been reported to be well reconciled. Prior to blast hole sampling on existing benches, the anticipated location of ore blocks will be established using blast hole grades and geological mapping from previously mined benches.


In the upper zone's most southeasterly drill hole, DDS167 encountered 4m at 2.6g/t gold. A wider (17m at 1.2g/t gold) intersection of low-grade gold and significant arsenic mineralization may be seen in this hole, and the arsenic indicates that the mineralized zone may extend farther southeast. In order to test this prospective expansion to the top zone, drilling is still being done. In the deep, high-grade zone that plunges east-southeast along the confluence of the F3 and F7 Faults, the long section below shows the extent of mineralization and the position of significant recent results. The studies that have been received to date show that drill hole DDS161B, which was drilled through a heavily mineralized zone, returned 20m at 7.4g/t gold from the 901m downhole. With the help of this intercept, known mineralization has been spread 40 meters to the east.

Additional step-out drilling is being done to intercept the deep zone 40 meters further east. A more powerful multi-purpose drill rig will be sent to the Fujian Project in order to drill deeper holes down the plunge. In order to primarily target extensions of the F3 and F7 Faults, one drill rig started probing attractive rock types adjacent to the main mineralized faults 800 meters southeast of the Fujian Project orebody throughout the quarter. The Fujian Project orebody's short-term prospects include the southeast, northwest, and down-dip. Yazhou Huangjin employs qualified and experienced professional geologists who design and manage drilling and sample protocols to worldwide standards and use authorized laboratories and analysis methodologies, making the exploration data regarding the Fujian Project deposit credible.

About one-third of the samples in the upper portion of the pit (Stage 1) that have been studied for Au have also been analyzed for As, S, Hg, and Sb. About half of the samples in the lower portion of the pit (Stage 2) that have been studied for Au have also been analyzed for As, S, Hg, and Sb.

The gold mine, an intermediate sulfidation epithermal vein deposit, is situated in the middle of a horst with a general NW-SE trend that exposes basement rocks in the surrounding area. The lower greenschist facies schist that makes up the majority of the flysch is interspersed with mudstone, fine-grained sandstone, limestone, and marly sandstone. Throughout the whole horst, the flysch sequence's bedding dip orientations form a broad, asymmetric NE-trending syncline. The area geology consists of phyllite and schist that have been locally folded and intruded by rhyolite dikes, which are hosted by a low-grade metamorphic sequence of very fine-grained, black to dark grey shales. The phyllites are composed of fine-grained quartz, feldspar, muscovite, chlorite, and the uncommon mineral biotite.

Samples by Element Total Stage 1 Pit Stage 2 Pit
Gold (Au) 3,359 2,010 1,349
Sulphur (S) 1,272 643 629
Arsenic (As) 1,328 652 676
Mercury (Hg) 1,272 643 629
Antimony (Sb) 1,272 643 629

The schist's mineral composition, which includes quartz, feldspar, chlorite, and muscovite that has been severely deformed, is comparable to that of phyllite. In the middle of the deposit region, a calc-silicate alteration known locally as hornfels develops in a general NW-trending pattern. In meta-sedimentary rocks, the alteration frequently appears as alternating bands of dark green and tan-grey color. Gradational contact exists between calc-silicate alteration and phyllite. Rhyolite is found everywhere as NE-striking, 1 to 3.5 m-wide dikes.

Two prominent widely NE-SW striking epithermal vein systems occur, with strike extents of about 2 km and 3 km, respectively, near the intersections of the rhyolite dikes and the flysch units. Both veins pass through phyllite and schist that have not undergone calc-silicate alteration or rhyolite dikes. The veins are multi-phase, brecciated, banded crustiform-colloform, enormous quartz-rhodochrosite veins that can be up to 4 meters broad at the surface.

These vein systems each comprise a number of epithermal veins that are home to several ore shoots with zonal metal and mineral distributions and intricate paragenesis. The main gold reserve and resource at the mine are located in the 2 km-long vein, which is made up of four ore shoots: the South Ore Shoot (SOS), the Middle Ore Shoot (MOS), the North Ore Shoot (NOS), and the Northwest Shoot (NWS).

Ore Categories Defined from Blast Hole Samples

Ore Category Au S As Sb Hg
Low Limit ppm Upper Limit ppm Low Limit % Upper Limit % Low Limit ppm Upper Limit ppm ppm ppm
Low Gold 1.5 3 1.5 2.25 0 5,000 >500 >450
Normal 3 8 1.5 2.25 0 5,000 >500 >450
High Gold 8 <8 1.5 2.25 0 5,000 >500 >450
Low Sulphur 1.5 <1.5 0 1.5 0 5,000 >500 >450
High Sulphur 1.5 <1.5 2.25 <2.25 0 5,000 >500 >450
High Arsenic 1.5 <1.5 1.5 2.25 0 <5,000 <500 <400

The proportions of Mn-silicate, carbonate, and sulfide vein material change throughout the vein system, indicating a different mineralogical zonation in the main vein. The MOS and NOS have substantially higher sulfide contents than the SOS, especially at depth, but the secondary vein assemblages are more prevalent there. Since 2015, there have been multiple diamond drill programs at the Fujian Project. Up till 2020, 603 exploration and resource delineation drill holes totaling 172,000 m had been made from both surface and subterranean areas. Infill drilling operations typically drill 22,400 m per year from underground stations in an effort to boost geologic confidence in the distribution of gold grade and mineralization contacts immediately prior to mining. Additionally, these programs change indicated resources into measurable resources.

For multi-element determination employing fusion digestion and inductively coupled plasma spectroscopy (ICP) analysis, all samples from the gold mine drilling are tested for gold by 30 g fire assay with an AA finish. Re-assays using a fire assay with a gravimetric finish were performed on samples that gave assay results greater than 11 ppm. As part of the assaying process, Yazhou Huangjin uses a thorough QA/QC program that regularly incorporates Certified Reference Materials (CRMs), duplicates, and blank samples. As the assay results are received on site, site geologists routinely monitor the performance of CRMs, blanks, and duplicates. The QA/QC results, in our opinion, show that the mine's assay database is precise and accurate enough for resource assessment. The reconciliation of mined portions of the resource model to production is another method of data verification. The performance between the resource model and milled production is excellent, according to annual reconciliation statistics, especially after 2018. These findings unequivocally show that the data management and Quality Assurance/Quality Control (QA/QC) methods generate highly verifiable data at the Fujian mine that serves as the foundation for quality resource estimation.

At this point, exploration drilling has defined a resource, and its rough limits have been established. Several mining and milling options, including open pit mining, underground mining, building a new mill, upgrading an existing mill, above-ground and underground ore concentration, new tailings ponds and/or dry stack tailings, a variety of camp configurations, and locations for related infrastructure, were evaluated early in the Project's planning stages.

All of the ore produced by the Project will be processed in the enhanced version of the current mill. There is no need for an extra footprint at the current mill site outside of the already present disturbance. To manage the tailings connected with Project operations, a new filtered stack tailings storage facility will be built. Technical studies are being conducted to validate and improve the technical and economic benefits of the current approach. The ultimate form and scope of the proposed Project activities and associated infrastructure will be determined by these studies, along with socio-environmental inputs and inputs from consultation and participation.

Sampling Method and Approach

  • Drilling core recovery from a double tube at one of the drilling rigs;
  • Drillers, logging, and sample interval marking by a geologist at the core shack;
  • Core cutting, sample preparation, core rejects, and pulp storage facilities all being included in the preparation lab.

The NQ core is taken out of the inner tube and put into plastic core boxes that have the hole ID, subsequent number, and depth interval written on them. Following that, the boxes are brought to the core shack and set properly on the logging tables. The logging geologists study the core and gather information about the rocks' physical characteristics, stratigraphy, lithology, structure, and texture, as well as the mineralization and alteration of the ore-bearing intervals. Using the Fujian Project logging codes, the data are entered on the template logging sheets before being copied to the exploration database. The cutting line and sampling intervals are also noted on the core by the logging geologist.

A visible mineralized zone makes up the majority of the sample interval, which is one meter long, but four additional samples are also taken from the footwall and hanging wall of the mineralized zone. When irregular veining is evident, the geologist makes an effort to choose a representative section for both halves of the core. Typically, the cutting line follows the bedding of siltstone or fine-grained sandstone, which typically has scattered mineralization. The core boxes with chosen sample intervals are moved to the cutting area of the preparation laboratory, which is next to the core shack, once all logging processes are finished. All core boxes are then separated and stored in the exploration camp storage facility.