Drilling exploration efforts by Hudbay Minerals, owner of the proposed Rosemont Mine, have discovered four copper deposits that could bring several open-pit mining projects within view of Green Valley and Sahuarita.
In an announcement Monday, Hudbay said the lodes are of higher grade and closer to the surface than Rosemont, and that more drilling and exploration is necessary to make determinations on next steps.
Hudbay Minerals drilled in three locations in 2020-21, on the western side of the Santa Ritas:
•Near the ridgeline 11 miles east of Quail Creek;
•About a half-mile north-northwest of that site;
•In the Peach Elgin area just south of the Santa Rita Quarry -- the white limestone mine visible at the northern end of the Santa Ritas.
All locations are on Hudbay land in the Helvetia Mining District.
Hudbay expanded those efforts to six drill rigs earlier this year after "encouraging initial results," according to a release. Hudbay made it clear there is more exploration to be done but the find could conceivably lead to anywhere from one to four open-pit mines in the area, which spreads for several kilometers.
Andre Lauzon, vice president of Hudbay Minerals’ Arizona Business Unit, answered questions via email on the new find for the Green Valley News.
1. In layman's terms, how big is this deposit?
Additional exploration and analysis is required to fully understand the size. What we have confirmed is the discovery of four new deposits of high-grade sulphide and oxide mineralization at and near the ground surface. The combined surface exposure (strike length) of the deposits is several kilometers long. The exploration program that is currently underway will focus on understanding the full extent of the deposits as well as following up on other interesting intersections beyond the limits of these new deposits but still within our private land limits.
2. How does it compare to Rosemont?
Current drilling indicates that the copper mineralization contains higher grades closer to the surface than Rosemont. The stripping ratio, a term that compares the amount of waste rock that must be removed to access the copper mineralization, is much less than at Rosemont.
3. Does it have a name?
Yes, Copper World. Copper World is the name for the area where all four deposits are located. The four new deposits discovered are called Peach, Elgin, Copper World and Broad Top Butte. The Copper World area has a rich history of mining from 1874 to 1969, during which time more than 20 small underground mines operated.
4. Hudbay has been exploring three areas on the western slope of the Santa Ritas; where are the deposits exactly?
Please see the VRIFY link provided in the press release.
5. What's there of value besides copper? Is there a percentage breakdown?
These deposits also contain some silver and molybdenum. The details are provided in the press release.
6. Explain the digital models you're making available online to give people a better idea of what's down there; where can we find them.
To enable our stakeholders to better understand Copper World, we are providing an interactive online tool that includes 3D visualization of the four deposits, and 360-degree aerial and ground imagery of their locations. We provided a link to this tool in our press release and it can also be accessed via hudbay.com and through our social media.
7. Has the decision been made to mine the site(s)? If not, when can we expect that?
No, it is too early in the process. As stated by our COO, “Copper World has the potential to host at least four economic deposits with a relatively low strip ratio and may prove to be a viable open-pit operation that is either separate or additive to our Rosemont project.” If our analysis of the data shows that it is feasible, we will share those details with the public as they are available.
8. If you made the decision today to mine, when is the earliest we could see digging?
We anticipate multiple phases of drilling to be completed before we can develop a mine plan with proposed facility layout and processing strategy. Once we fully understand what we have, we should be able to estimate timelines for development.
9. Could there be more than one mine site stemming from this new find?
Based on our current exploration program, there could be multiple open pits within Copper World. As our COO shared, the Copper World project could be operated either as a separate project or to enhance the Rosemont Project.
10. Do you know enough now to determine whether it would be open pit vs. underground mining? That decision rests on what?
These near surface deposits would be amenable to open pit surface mining.
11. Would you need use of any public lands to mine these sites, as is the case with Rosemont? If not, does that speed up the permitting process?
Our drilling program has been exclusively on private land. It is too early to determine if any public lands will be required for any future mine plan.
12. Residents already are concerned about Rosemont's estimated water usage. Does the area have the water to support another major mining operation? How is that determined?
The Rosemont Project was permitted as a net neutral water operation, since it requires recharging more CAP water than is pumped. The amount of water a Copper World project would require and any related mitigation, will be determined by the future mine plan. Hudbay designs and operates its mines in a responsible and sustainable manner that ensures local communities benefit from our presence.
13. Would dry-stack tailings be considered, and what's the benefit?
A new project design would take advantage of new technologies and best practices to optimize operations, and minimize the impacts on scarce resources such as water. Dry stack tailings will be considered.
14. As the crow flies, how far are the nearest homes, and where are they? What's the nearest major housing development?
There are several homes within a mile of the Copper World area, most are off of South Helvetia Road before reaching the site. Corona de Tucson is approximately six miles north and Quail Creek is approximately eight miles west from the nearest part of Copper World.
15. Would people living in Green Valley and Sahuarita see the operation once it's up and running? Who else would be able to see it — parts of Tucson, Vail, Corona de Tucson? Who would likely hear the day-to-day operations?
It is likely that some parts of Copper World and its operations would be visible from Green Valley and Sahuarita. What and how much will be visible depends on the future mine plan and the scale of a new project. From Corona de Tucson looking south there are some natural features that will block the view of Copper World but some parts of an operation may still be visible. The Vail community is unlikely to see any part of Copper World. It is unlikely that the sounds would be audible beyond a mile or two from the operation.
16. Where would the truck route likely be located? Would a rail spur be considered for the new operation(s)?
It is too early to know what transportation options may be utilized.
17. Are you willing to give tours of the site to area residents? Media? If not, would investors be offered tours — and what's the difference?
At the moment, there are multiple drilling rigs and heavy equipment operating on site and we are not able to offer site tours. We have developed the online visualization tool that allows anyone to explore the area in a way that is likely more effective than an in-person tour while also eliminating the risk of exposures at site.
18. What's the next step beyond attracting investors?
See responses to questions 1 and 8. We are committed to working with our neighbors and all stakeholders to ensure that we minimize impacts, such as noise and visual impacts that may result from our operations, while providing significant benefits in terms of jobs and economic activity.
19. Briefly explain the permitting process. Rosemont involved 17 agencies; is it that involved?
It is impossible to describe the permitting process without understanding the mine plan. All mines in the United States are required to meet federal air and water quality standards, regardless of whether they are on private or federal land. In Arizona, the State issues permits to ensure these standards are met and also has a groundwater quality permitting program. Each of these permits include opportunities for public comment and input.
20. When can we expect definitive news on the future of the site?
There are numerous milestones that need to be achieved prior to determining the future of the site, and timing at this early stage is uncertain. We will provide updates as milestones are achieved and share information as we are doing now.
21. Are you currently exploring anywhere else in Southern Arizona? Where?
No, Copper World is currently our only exploration program in Arizona.
22. Does this change anything about Rosemont’s mine plan?
Hudbay remains fully committed to the Rosemont Project. The delay to Rosemont gave us the time and opportunity to explore other areas of our private property for possible mineral deposits. This exploration will not affect our ability to move forward with the Rosemont Project once all legal and other permitting related issues have been resolved.
23. Does the CAP line play into this at all?
We have a long-standing partnership with Community Water Company of Green Valley to recharge CAP water farther south in Green Valley than is possible today (Project RENEWS). We continue to advance this project and are confident that it will bring significant benefits to the groundwater balance in the area.