Potter-Cramer Mine

The Potter-Cramer Mine is located southwest of Wickenburg, in the Belmont Mountains, Maricopa County, Arizona. The mine was originally developed prior to the 1920s, and has produced lead, silver and gold. The earliest record of mining operations with the Bureau of Mines was in 1942, when the mine was called the Lost Spaniard. The mine was then operated by the Vulture Mining Company. Records indicate that only a small amount of ore was processed due to the troubles the owners had with labor.

In 1967, Dr. Sidney A. Williams, a Phelps Dodge research geologist, was collecting information on the geology of the Potter-Cramer Mine. While studying the geology, Dr. Williams collected several specimens. One of the specimens collected, contained a new mineral species. The new mineral was called wickenburgite, and was approved by the International Mineralogical Association in 1968. Since the Potter-Cramer Mine was now the Type Locality for wickenburgite, samples were sent to the Smithsonian Institution for their vast collection.

Wickenburgite is a rare lead aluminum calcium silicate hydroxide Pb3Al2CaSi10O24(OH)6. Wickenburgite is usually white, colorless or in rare instances pink. It is well crystallized to granular, with hexagonal crystals ranging from 0.2 to 1.5 mm across. Most wickenburgite is found as micro crystals in spongy aggregates. The host rock for the wickenburgite is a rhyolite breccia. The wickenburgite is an oxide zone mineral, found in veins and fractures within the host rock. These veins and fractures originally contained deposits of galena and sphalerite. Gangue minerals present in these veins are mostly quartz and fluorite. Some other minerals found within these oxide zones include willemite, phoenicochroite, mimetite, pyromorphite, galena, chalcedony, cerussite and crocoite among others. Wickenburgite is the most abundant mineral present at the mine, and was among the last to crystallize.

Several minerals have been found to fluoresce at the Potter-Cramer Mine. These minerals include wickenburgite, willemite, fluorite, chalcedony and cerussite. Wickenburgite fluoresces best under shortwave ultraviolet light, with a response ranging from Bazooka bubble gum pink (for those who are old enough to remember Bazooka bubble gum) to deep crimson red. Willemite fluoresces best under shortwave ultraviolet light, with a response ranging from creamy yellow/white to green. The willemite is also phosphorescent. Fluorite fluoresces under both longwave and shortwave ultraviolet light, with longwave providing the best result. The fluorescent response for the fluorite is typical europium activated purple. The fluorescent chalcedony was only identified after I claimed the mine in 2002. Manny Robbins had described it in his second book as the unknown mineral that fluoresced “cornflower blue.” The chalcedony does fluoresce a beautiful cornflower blue under shortwave ultraviolet light, but is not as common as the wickenburgite, willemite and fluorite. The least common fluorescent mineral found so far at the Potter-Cramer Mine is cerussite. In some specimens, small amounts of cerussite will fluoresce yellow under longwave ultraviolet light. I should mention that some fluorescent caliche can be found at the Potter-Cramer Mine that fluoresces yellow/orange as well, so it’s best not to get the two minerals confused.

I first collected at the Potter-Cramer Mine in 1986, when I moved to Arizona. On the dumps I did find specimens that contained wickenburgite, willemite and fluorite. These were very attractive three color specimens. I kept some for my own collection, and offered others for sale through Polman Minerals. All in all, I may have collected at the mine five or six times in the late 1980s and early 1990s. In 2002, I found out that the Potter-Cramer Mine was open to claim. I later went out to the mine, staked my claim, filed the proper paperwork with the Bureau of Land Management and became the mine owner a month or so later.

The entrance to the mine is a vertical shaft that is approximately 60 feet deep. At the bottom of the mine there is a drift which leads to a big open stope. At the far end of the stope, the ore was gravity fed down a 5-foot wooden ore shoot. From there an ore cart ran on rail to an exit which has since been sealed off. Unfortunately for me, the ore cars had been removed early in the mine history, but the rail was still left in place.

I did some small-scale mining in 2002, when getting/using explosives was still relatively easy. Working a small mineralized seam at the surface near the vertical shaft, we drilled and blasted the rock. I obtained several flats of decent specimens for sale, but did not mine further once the strict explosives laws took affect shortly thereafter.

In October of 2016, I decided it was time to do some much larger scale mining for specimens at the Potter-Cramer Mine. With the help of four good friends, David Giebelstein, Mike Sawicki, Nate Johnson and Phil Smith, we spent the weekend of October 29, 2016 mining. Without explosives, we decided to just use a rock drill, jackhammer and expansion grout to work the mineralized zone near the vertical shaft of the mine. The rock was hard, and following the mineralized vein was difficult. After a full weekend of work, we moved a lot of rock, and managed to collect some of the finest specimens of wickenburgite that have ever been produced from the mine. Below I have provided a few pictures of the mine, and mining operations.

A great photograph of the Potter-Cramer Mine taken by my good friend Al Liebetrau in 2004.
The vertical shaft at the Potter-Cramer Mine. The photograph was taken by Mike Sawicki on 10/29/16
Here is the drift leading to the main open stope. The photograph was taken in 2003.
A photograph taken in 2016, showing a nice vein of galena in the main open stope.
Here I am next to the ore shoot on the second level of the mine. Photograph taken on 10/29/16 by Phil Smith.
Here is a view of the vertical shaft. It takes a 40-foot and a 20-foot ladder to reach the bottom of the shaft. The photograph was taken on 10/29/16.
Nate Johnson (left) and me, drilling the rhyolite breccia to get access to the mineralized vein beneath. The photograph was taken by Mike Sawicki on 10/29/16.
From left to right, my good friends, David Giebelstein, Nate Johnson, Mike Sawicki and Phil Smith. All five of us were exhausted after a full weekend of mining. The photograph was taken on 10/29/16.

The specimens offered for sale below were photographed using a 36-watt shortwave ultraviolet lamp. I did not use longwave ultraviolet light during photography because it tended to make the fluorescent purple fluorite over-power the wickenburgite. In most specimens, you still can see the fluorescent fluorite present, even under shortwave ultraviolet light only. Since some of the rhyolite host rock was brecciated, some of the specimens may tend to be a bit crumbly and shed slightly. Prices for the most part are based on the amount of the rarer wickenburgite present in the specimen. However, some specimens are very aesthetic when they contain three or four different fluorescent minerals, and are also priced accordingly.

To order a specimen from this Showcase, just email or call with the number you wish to purchase. When a specimen is sold it will be marked SOLD in red. When new specimens are posted, sold specimens will be deleted, and new specimens added in their place.

For quick email access to purchase a specimen, you may click here.

PC-146

White Light

Shortwave Ultraviolet

Name & Location: Wickenburgite, Willemite, Fluorite, Potter-Cramer Mine, Maricopa County, Arizona.
Size: 9 x 5 x 5-inches
Price: $500.00

PC-145 SOLD

White Light

Shortwave Ultraviolet

Name & Location: Wickenburgite, Willemite, Potter-Cramer Mine, Maricopa County, Arizona.
Size: 5 x 3 x 3-inches
Price: $400.00 SOLD

PC-144

White Light

Shortwave Ultraviolet

Name & Location: Wickenburgite, Willemite, Fluorite, Potter-Cramer Mine, Maricopa County, Arizona.
Size: 5 x 4.5 x 3-inches
Price: $500.00

PC-143

White Light

Shortwave Ultraviolet

Name & Location: Wickenburgite, Willemite, Potter-Cramer Mine, Maricopa County, Arizona.
Size: 4.5 x 3.5 x 2.5-inches
Price: $400.00

PC-142 SOLD

White Light

Shortwave Ultraviolet

Name & Location: Wickenburgite, Chalcedony, Potter-Cramer Mine, Maricopa County, Arizona.
Size: 4.5 x 3.5 x 2-inches
Notes: Specimen contains rare “cornflower blue” chalcedony.
Price: $300.00 SOLD

PC-141

White Light

Shortwave Ultraviolet

Name & Location: Wickenburgite, Willemite, Fluorite, Potter-Cramer Mine, Maricopa County, Arizona.
Size: 5 x 4.5 x 4-inches
Price: $500.00

PC-140

White Light

Shortwave Ultraviolet

Name & Location: Wickenburgite, Willemite, Fluorite, Potter-Cramer Mine, Maricopa County, Arizona.
Size: 10 x 5 x 5-inches
Price: $400.00

PC-139 SOLD

White Light

Shortwave Ultraviolet

Name & Location: Wickenburgite, Willemite, Fluorite, Potter-Cramer Mine, Maricopa County, Arizona.
Size: 3.5 x 2 x 2-inches
Price: $200.00 SOLD

PC-138 SOLD

White Light

Shortwave Ultraviolet

Name & Location: Wickenburgite, Willemite, Fluorite, Potter-Cramer Mine, Maricopa County, Arizona.
Size: 3 x 2.5 x 1-inches
Price: $100.00 SOLD

PC-137

White Light

Shortwave Ultraviolet

Name & Location: Wickenburgite, Willemite, Fluorite, Potter-Cramer Mine, Maricopa County, Arizona.
Size: 4 x 2 x 2-inches
Price: $100.00

PC-136 SOLD

White Light

Shortwave Ultraviolet

Name & Location: Wickenburgite, Willemite, Fluorite, Potter-Cramer Mine, Maricopa County, Arizona.
Size: 3.5 x 3 x 2.5-inches
Price: $150.00 SOLD

PC-135 SOLD

White Light

Shortwave Ultraviolet

Name & Location: Wickenburgite, Willemite, Fluorite, Potter-Cramer Mine, Maricopa County, Arizona.
Size: 4.5 x 4 x 3-inches
Price: $300.00 SOLD

PC-134 SOLD

White Light

Shortwave Ultraviolet

Name & Location: Wickenburgite, Willemite, Fluorite, Potter-Cramer Mine, Maricopa County, Arizona.
Size: 2.5 x 2.5 x 1.5-inches
Price: $75.00 SOLD

PC-133

White Light

Shortwave Ultraviolet

Name & Location: Wickenburgite, Willemite, Fluorite, Potter-Cramer Mine, Maricopa County, Arizona.
Size: 4 x 2.5 x 1.5-inches
Price: $65.00

PC-132 SOLD

White Light

Shortwave Ultraviolet

Name & Location: Wickenburgite, Chalcedony, Potter-Cramer Mine, Maricopa County, Arizona.
Size: 4 x 3 x 2-inches
Notes: Specimen contains rare “cornflower blue” chalcedony.
Price: $200.00 SOLD

PC-131 SOLD

White Light

Shortwave Ultraviolet

Name & Location: Wickenburgite, Willemite, Fluorite, Potter-Cramer Mine, Maricopa County, Arizona.
Size: 3 x 3 x 1.5-inches
Price: $75.00 SOLD

PC-130

White Light

Shortwave Ultraviolet

Name & Location: Wickenburgite, Willemite, Potter-Cramer Mine, Maricopa County, Arizona.
Size: 3 x 2.5 x 2-inches
Price: $75.00

PC-129 SOLD

White Light

Shortwave Ultraviolet

Name & Location: Wickenburgite, Chalcedony, Potter-Cramer Mine, Maricopa County, Arizona.
Size: 2 x 2 x .75-inches
Notes: Specimen contains rare “cornflower blue” chalcedony.
Price: $50.00 SOLD

PC-128 SOLD

White Light

Shortwave Ultraviolet

Name & Location: Wickenburgite, Willemite, Fluorite, Cerussite, Potter-Cramer Mine, Maricopa County, Arizona.
Size: 2.75 x 2.5 x 1.5-inches
Notes: Specimen contains rare cerussite not seen in photograph.
Price: $150.00 SOLD

PC-127 SOLD

White Light

Shortwave Ultraviolet

Name & Location: Wickenburgite, Willemite, Fluorite, Potter-Cramer Mine, Maricopa County, Arizona.
Size: 3.5 x 2 x 1.5-inches
Price: $150.00 SOLD

PC-126

White Light

Shortwave Ultraviolet

Name & Location: Wickenburgite, Willemite, Fluorite, Potter-Cramer Mine, Maricopa County, Arizona.
Size: 3.5 x 3.5 x 2-inches
Price: $200.00

PC-125 SOLD

White Light

Shortwave Ultraviolet

Name & Location: Wickenburgite, Willemite, Fluorite, Potter-Cramer Mine, Maricopa County, Arizona.
Size: 4.5 x 2.5 x 1.5-inches
Price: $300.00 SOLD

PC-124

White Light

Shortwave Ultraviolet

Name & Location: Wickenburgite, Willemite, Potter-Cramer Mine, Maricopa County, Arizona.
Size: 7 x 4 x 4-inches
Price: $500.00

PC-123

White Light

Shortwave Ultraviolet

Name & Location: Wickenburgite, Willemite, Fluorite, Potter-Cramer Mine, Maricopa County, Arizona.
Size: 5.5 x 5.5 x 3-inches
Price: $400.00

PC-122 SOLD

White Light

Shortwave Ultraviolet

Name & Location: Wickenburgite, Willemite, Fluorite, Chalcedony, Potter-Cramer Mine, Maricopa County, Arizona.
Size: 6 x 3.5 x 2.5-inches
Notes: Specimen contains rare “cornflower blue” chalcedony.
Price: $450.00 SOLD

PC-121 SOLD

White Light

Shortwave Ultraviolet

Name & Location: Wickenburgite, Willemite, Fluorite, Potter-Cramer Mine, Maricopa County, Arizona.
Size: 3.5 x 3 x 1.5-inches
Price: $200.00 SOLD

PC-120 SOLD

White Light

Shortwave Ultraviolet

Name & Location: Wickenburgite, Willemite, Fluorite, Chalcedony, Potter-Cramer Mine, Maricopa County, Arizona.
Size: 3.5 x 2.5 x 1.5-inches
Notes: Specimen contains rare “cornflower blue” chalcedony.
Price: $150.00 SOLD

PC-119 SOLD

White Light

Shortwave Ultraviolet

Name & Location: Wickenburgite, Willemite, Fluorite, Potter-Cramer Mine, Maricopa County, Arizona.
Size: 3.5 x 2.5 x 1.5-inches
Price: $150.00 SOLD

PC-118 SOLD

White Light

Shortwave Ultraviolet

Name & Location: Wickenburgite, Willemite, Fluorite, Chalcedony, Potter-Cramer Mine, Maricopa County, Arizona.
Size: 4.5 x 3.5 x 2.5-inches
Notes: Specimen contains rare “cornflower blue” chalcedony.
Price: $300.00 SOLD

PC-117

White Light

Shortwave Ultraviolet

Name & Location: Wickenburgite, Willemite, Fluorite, Potter-Cramer Mine, Maricopa County, Arizona.
Size: 7 x 4.5 x 2-inches
Price: $500.00

PC-116 SOLD

White Light

Shortwave Ultraviolet

Name & Location: Wickenburgite, Willemite, Potter-Cramer Mine, Maricopa County, Arizona.
Size: 3.5 x 3 x 2-inches
Price: $350.00 SOLD

PC-115

White Light

Shortwave Ultraviolet

Name & Location: Wickenburgite, Willemite, Fluorite, Potter-Cramer Mine, Maricopa County, Arizona.
Size: 7 x 7 x 3.5-inches
Price: $500.00

PC-114

White Light

Shortwave Ultraviolet

Name & Location: Wickenburgite, Willemite, Potter-Cramer Mine, Maricopa County, Arizona.
Size: 6.5 x 4 x 2-inches
Price: $350.00

PC-113 SOLD

White Light

Shortwave Ultraviolet

Name & Location: Wickenburgite, Willemite, Fluorite, Potter-Cramer Mine, Maricopa County, Arizona.
Size: 7 x 4 x 2.5-inches
Price: $600.00 SOLD

PC-112

White Light

Shortwave Ultraviolet

Name & Location: Wickenburgite, Willemite, Fluorite, Potter-Cramer Mine, Maricopa County, Arizona.
Size: 4.5 x 3 x 1.5-inches
Price: $350.00

PC-111 SOLD

White Light

Shortwave Ultraviolet

Name & Location: Wickenburgite, Willemite, Fluorite, Potter-Cramer Mine, Maricopa County, Arizona.
Size: 5.5 x 3.5 x 3-inches
Price: $500.00 SOLD

PC-110

White Light

Shortwave Ultraviolet

Name & Location: Wickenburgite, Willemite, Fluorite, Cerussite, Potter-Cramer Mine, Maricopa County, Arizona.
Size: 3.5 x 3.5 x 1.5-inches
Notes: Specimen contains rare cerussite not seen in photograph.
Price: $300.00

PC-109 SOLD

White Light

Shortwave Ultraviolet

Name & Location: Wickenburgite, Willemite, Fluorite, Chalcedony, Potter-Cramer Mine, Maricopa County, Arizona.
Size: 4.5 x 3 x 2-inches
Notes: Specimen contains rare “cornflower blue” chalcedony.
Price: $300.00 SOLD

PC-108 SOLD

White Light

Shortwave Ultraviolet

Name & Location: Wickenburgite, Willemite, Potter-Cramer Mine, Maricopa County, Arizona.
Size: 5 x 3 x 2-inches
Price: $350.00 SOLD

PC-107 SOLD

White Light

Shortwave Ultraviolet

Name & Location: Wickenburgite, Willemite, Fluorite, Chalcedony, Potter-Cramer Mine, Maricopa County, Arizona.
Size: 5 x 4 x 2.5-inches
Notes: Specimen contains rare “cornflower blue” chalcedony.
Price: $400.00 SOLD

PC-106

White Light

Shortwave Ultraviolet

Name & Location: Wickenburgite, Willemite, Potter-Cramer Mine, Maricopa County, Arizona.
Size: 7 x 5 x 5-inches
Price: $500.00

PC-105

White Light

Shortwave Ultraviolet

Name & Location: Wickenburgite, Willemite, Fluorite, Potter-Cramer Mine, Maricopa County, Arizona.
Size: 5.5 x 4 x 4-inches
Price: $500.00

PC-104

White Light

Shortwave Ultraviolet

Name & Location: Wickenburgite, Willemite, Fluorite, Potter-Cramer Mine, Maricopa County, Arizona.
Size: 12 x 7 x 3-inches
Price: $800.00

PC-103 SOLD

White Light

Shortwave Ultraviolet

Name & Location: Wickenburgite, Willemite, Fluorite, Potter-Cramer Mine, Maricopa County, Arizona.
Size: 5 x 3.5 x 3-inches
Price: $400.00 SOLD

PC-102

White Light

Shortwave Ultraviolet

Name & Location: Wickenburgite, Willemite, Fluorite, Potter-Cramer Mine, Maricopa County, Arizona.
Size: 6 x 4 x 2.5-inches
Price: $400.00

PC-101 SOLD

White Light

Shortwave Ultraviolet

Name & Location: Wickenburgite, Willemite, Fluorite, Potter-Cramer Mine, Maricopa County, Arizona.
Size: 7 x 5 x 2.5-inches
Notes: Ex. George V. Polman Collection #2563.
Price: $500.00 SOLD

PC-100 SOLD

White Light

Shortwave Ultraviolet

Name & Location: Wickenburgite, Willemite, Fluorite, Potter-Cramer Mine, Maricopa County, Arizona.
Size: 7.5 x 3.5 x 2.5-inches
Price: $600.00 SOLD