Project of the Week: Silver Bullet Mines - Black Diamond

31st January 2022

 

 

Junior Mining Companies. Let’s repeat that title — Junior. Mining. Companies. There are many definitions of those words, and in our field, we often refer to juniors as those companies in the early phases of project development, generally below $20 M in stock movement. Many of those companies make their footprint in our community through exploration of new mineral projects and expansion of existing resources. So….are we forgetting about the mining?

Silver Bullet Mines Corp (TSx: SBMI) is actually a junior mining company! Spending over $1.5 million (USD) from personal funds, and more than $4.5 million (USD) from investors, Silver Bullet Mines has worked to reopen the historic Buckeye Silver Mine near Globe, Arizona, USA. Their claims on the Black Diamond Property cover ~20 km2 and includes 5 historic mines, including the Buckeye and McMorris mines which have never been properly explored (Fig. 1).  Modern exploration of the property started in 2013, with nearly C$5 million invested in the projected before Silver Bullet acquired the property in 2020 from Black Diamond Exploration Inc., with several of the SBMI directors pooling together to continue working the property.

Figure 1. Location of the Black Diamond Property and major producers in the district. The Globe-Miami district lies about 100 km east of Phoenix, Arizona, USA.

The project area is in a world-class metal province, with several majors operating nearby, such as Freeport McMoran’s Miami-Inspiration complex which produce ~60 million lbs of copper annually. Rio Tinto’s world-class Resolution copper porphyry deposit lies about 50 km to the southwest and contains 1.787 billion metric tonnes at an average grade of 1.5% copper (www.resolutioncopper.com). Active mining and few environmental restrictions make the mining district favorable for exploration and exploitation. The Black Diamond property contains several styles of mineralization, such as Ag veins, Cu skarns, and the potential for porphyry Cu as well. Let’s take a peek at some of these targets, starting with the company’s primary target, the Buckeye Mine (Fig. 2).

Figure 2. Map of the Black Diamond Property with locations of targets identified by Silver Bullet Mines based on historical producers and previous exploration data.

Buckeye Mine

The local geology consists of Proterozoic sedimentary rocks and diabase sills which have been intruded intermediate composition igneous rocks during the Laramide Orogeny in the Paleogene, bringing metal to the district. Mineralization at the Buckeye target occurs as discrete silver veins which host argentite (Ag2S) and cerargyrite (AgCl), accompanied by barite and quartz, an assemblage characteristic of low-sulfidation epithermal systems. It remains one of the most attractive targets for SBMI because of the ease of access of ore-grade material. In 2018, 500 oz of silver were produced from the Buckeye Mine in a test run, proving the viability of the new facility.

Figure 3. Mine shaft of the McMorris Mine. This entrance has been repaired and renovated to ensure modern safety standards are met for extractiona nd rehabilitation of the historically producing mine.

McMorris Mine (and vicinity)

The McMorris Mine is located in the northern part of the Black Diamond property in a geological feature called the Richmond Basin, which hosts other historical producers and silver deposits on the property (e.g., the Jumbo Mine). Hosted in a similar Proterozoic sedimentary sequence and diabase sills/dikes, Laramide-age intrusions include a quartz diorite and andesitic porphyry unit. Mineralized veins are traceable up to 2 km along strike roughly parallel with the lithological contact. Ore minerals in the Richmond Basin targets consists of native silver, chalcopyrite, tennantite, and argentite. In 2011, sample assays revealed ore grades in 5 of 6 trenches highlighted by a 5m intersection averaging 1,032 g/t Ag. Combined with soil geochemistry and hyperspectral analyses, multiple targets have been defined in the Richmond Basin (Fig. 4). The polymetallic metal endowment Ag-Pb-Zn-Cu is again indicative of the near-porphyry environment and provides an attractive range of commodities for SBMI to work with!

Figure 4. Map of soil geochemical data taken during a 2011 surface sampling project by Trueclaim Exploration Inc. These data highlight several of the target locations, including the Black Copper prospect in the southwest part of the property.

Black Copper Prospect

The other two silver mines provide up-front, already discovered systems which Silver Bullet plans to mine and expand, but there is a chance that those targets barely scratch the surface of the Black Diamond property. The Black Copper prospect occurs at the intrusive contact between the quartz diorite and a limestone unit, with magnetic anomalies extending up to 600 m wide. A 4 m wide magnetite vein outcrops at the surface near some old exploration adits, and returned assay results of 3.22 % Cu and 1.14 g/t Au, and 5.9 g/t Ag. The limestone host, replacement mineralogy, and metal assemblage of the Black Copper prospect suggest skarn-style mineralization which forms when hot, metal rich fluids interact with carbonate rocks.

That makes for three prospects, each of which is interesting in its own right, but which are all the more interesting together. Why? Because each of these mineralization styles is associated with porphyry Cu deposit models (Fig. 5; Sillitoe, 2010). With the presence of an andesitic porphyry unit and the intrusive quartz diorite on the Black Diamond property, it’s clear that intrusion-related mineralization was occurring nearby — but where? With a property nestled so close to other deposits in a world-renowned Cu porphyry district, it’s understandable to be exited for the discovery potential for Silver Bullet Mines!

Figure 5. Idealized model of the porphyry-epithermal environment modified from Sillitoe (2010). While the Black Diamond property contains no evidence for high sulfidation epithermal mineralization,  the Buckeye, McMorris, and Black Copper deposits hint at deeper porphyry-style mineralization.

Rehabilitating historical mines isn’t easy work. Silver Bullet Mines is currently in the final stages of construction of a production plant capable of handling 125 million tons (of ore) per day (www.silverbulletmines.com). Silver Bullet Mines also runs their own assay lab, which has been validated and verified by a 3rd party, allowing for daily assessment of ore grades. The current plan is production at Buckeye in Q1 of 2022, with the McMorris Mine producing before 2024. Refurbishing of mining infrastructure at the historical mines has (and will) create safe mining environments, and infrastructure will continue to be developed in relation to mining and processing. The revenue generated from silver production at the historical sites (as well as a “back up” property in Idaho yielding promising results) will fund exploration around the Black Copper target. Stay tuned to Spotlight Mining and Silver Bullet Mines Inc. for new updates on a true junior mining (and exploration) company!

 

 

References:

Silverbulletmines.com

NI 43-101 Technical Report for the Black Diamond Property, Effective November, 2020 - https://www.silverbulletmines.com/_files/ugd/32cc69_8aafdcdcb7af4fe796069b3a6ba1d30b.pdf

Sillitoe, R.H., 2010. Porphyry copper systems. Economic geology105(1), pp.3-41.

Aaron Hantsche

View posts by Aaron Hantsche
Aaron Hantsche recently obtained his PhD in Geology from the University of Geneva in Switzerland, where he studied distal Pb-Zn skarn deposits in southern Bulgaria. Magmatic-hydrothermal deposits are his primary focus, with a bent towards geochemical vectoring tools and field geology. In addition to his work as a geologist, Aaron is a director for the science communication platform, Ore Deposits Hub. His passion for mineral deposits and geo-communication led him to join the Spotlight Mining writing team in October 2021.