Yavapai County

Big Reef Mill

This mica processing facility along Castle Hot Springs Road was built in 1963 for $100,000.

Big Reef is a mine and associated mill located in the Wickenburg Mountains eleven miles northeast of Morristown. Primarily operated in the 1960s, mill production was very sporadic as ore quality and legal issues presented problems. Mica and beryllium were the commodities processed on site. Today, numerous structures remain.

The area surrounding Big Reef was first prospected in the late 1950s. During this time, drilling took place in the hills around and 21 different mining claims were established by 1959. The claims were owned by Dee Cantwell who initially pursued copper and gold. Cantwell found that copper occurrences in the area were limited and discovered that mica was much more abundant.

He began construction on a mica mill and formed the Big Reef Mining Company by 1963. The mill was set to have a crusher, multiple shaking screens, hammermills, and air tables which would slowly break down and refine the ore. After falling ill due to heart issues, Cantwell eventually resumed work on construction, and by 1964, the mill had been completed. The cost of construction was around $100,000. 

A side view showing the multiple levels of the mill site.

Small workings in the surrounding hills fed the mill. The mines that fed the mill weren’t the usual deep or long tunnels, but a series of pits and surface diggings. The mica they were after was typically at or very near the surface. The mill primarily processed the ore from the Big Reef Mine (also called the Green Dragon), which occupied the hills to the south of the mill and included workings on the northwestern hills. Running at normal capacity, the mill was able to process around 30 tons every 24 hours.

By August of 1964, the mill had churned out 20 tons of 95% mica powder and a few hundred pounds of beryl. The mica concentrate sold at market between $25 and $50 per ton. The beryl, while more valuable, was processed as a byproduct and wasn’t as abundant in the area. The mill continued to run with limited success. The ore reserves were estimated to contain 6000-7000 tons of mica ranging from 10-90%.

An ore bin sits near the top of the mill and several metal stands for conveyor belts remain as well.

The large, yellow tank appears to have been a holding area for mica ore.

Dee Cantwell’s health began to fade and he looked into selling the operation to numerous out of state groups. A new mining assessment in 1966 estimated that the mines contained another 1.5 million tons of raw ore which could produce 400,000 tons of mica. No sale was reported and the mill continued to run off and on through 1966. 

The property was taken over by Wong Associated Enterprises who worked to expand the operation. Cantwell and the Big Reef Co.was still managing the work at the time. The operation had just five men working. It was estimated however that the mines & millsite could produce nearly 10,000 tons yearly with a yearly profit of $300,000. The ore reserves would allow the mill to continue operation for 28 years. Interestingly enough, in October of 1967 all work had been suspended. Mr. Cantwell found himself in county jail on three of attempted murder. It is unclear what the verdict or reasoning was, however the property was now tied up in legal disputes. Equipment was soon removed from the mine.

The Big Reef remained locked up and non-operational throughout 1969. After litigation and sale, the property was eventually taken over by the Mineral Mountain Mining Company. However, the mine sat idle for the next few years. The new company explored the option of converting the mill to a flotation type mill and processing other pegmatite minerals. However, by 1973, the mill remained idle with no work being performed. 

At this point it seemed like the mill would not operate again. The initial ore evaluations were perhaps exaggerated. The area proved to be not as much of a success as anticipated. Brief re-examination of the area in 1982, but proved to be too spoty. While future prospecting was considered justified, the Big Reef was never operated again. Last worked in 1967, the millsite has sat abandoned for 50 years.

Today, numerous structures still remain on the property. The ore bin, a large yellow storage tank, and numerous rock walls and chutes can be found above the cement pad. Small metal pieces remain scattered around where conveyor belts once stood to connect everything together. A fair amount of crushed mica ore can be seen throughout each level of the mill. Walking each level will give you a better understanding of how each step of the process would have worked, slowly refining the ore as it traveled to the bottom. The area surrounding the mill has unfortunately become an impromptu shooting ranch and trash dump. It is still a neat place to visit and can be reached via a short but rocky trail from Castle Hot Springs Road. The roads past the mill have deteriorated beyond use.

 
 
 

Sources:

  1. Arizona Department of Mining & Mineral Resources. "Big Reef File" - BigreefYavapai965b.pdf. Tucson, AZ: Arizona Geological Survey (AZGS). PDF. http://docs.azgs.az.gov/OnlineAccessMineFiles/A-B/BigreefYavapai965b.pdf

  2. "Big Reef Mine (Green Dragon Mine), Yavapai Co., Arizona, USA." Mindat.org. Hudson Institute of Mineralogy. Web. 13 Sept. 2020. <https://www.mindat.org/loc-69019.html>. 

  3. "Big Reef (MRDS #10113146)." Mineral Resource Data System (MRDS). United States Geological Survey (USGS). Web. 13 Sept. 2020. <https://mrdata.usgs.gov/mrds/show-mrds.php?dep_id=10113146>.