By Alan Goldstein
Although the mines of the Illinois-Kentucky fluorite district are no longer active, the thrill of discovery is still possible. The discovery described in this article was made in early May at the Hastie’s Mining Co. quarry near Cave in Rock. I have visited this site more times than I can count while leading university geology department trips and during the preparation of my major article on the district (Goldstein, 1997).
Geophysics professor Hal Noltimier of The Ohio State University arranged this particular trip. His objective was to obtain specimens of minerals and ores for the geology department’s collections, as part of his current personal mission to gather ore samples from mines around the world to enhance their teaching collections. We planned to go to specific places on the Hastie’s property as well as several other mine dumps to obtain samples.
In addition to Hal and his girlfriend, I invited geologist and friend Mark Easterbrook who traveled from the Charleston, South Carolina area to join us. Mark had collected with me in the past. Ron Stubblefield, curator of the Ben E. Clement Mineral Museum in Marion, Kentucky joined us as well. A Martin-Marietta geologist was to join us so we could check out their quarry east of the Hastie’s, but his plans fell though due to back problems.
The first stop on our itinerary was the Hastie’s quarry located in an area of the fluorite district called Spar Mountain. (It is actually an escarpment.) Their limestone and sandstone mining operation is visible from several miles away (see photo 1). Fluorite has not been the Hastie’s bread and butter for a number of years since the bottom fell out of the fluorspar market. The first thing we noticed was a new entry road to the scale house – straight and wide – much better than the previous road, which was actually a county road. We met at the office and followed Bob Hastie to a section of the pit not being mined the day we were visiting. We were out of the way of their heavy equipment.
The mined out area was 30 – 40 feet lower than during my last visit two years earlier. Previous collecting had been from the Lead mine (or Austin Lead mine) deposits in the upper Ste. Genevieve Limestone. This time, we collected from Minerva Oil Company’s mining operation in the 1950’s that was exposed during quarrying recently (see photo 2) in the middle of the Ste. Genevieve Limestone. Several tunnels were obvious. According to Don Hastie, their driller has experience that enables him to avoid or minimize the trouble caused by punching through the roof of the numerous mine tunnels, so they don’t break drill rods during their operations. The main inconvenience when they do penetrate is plugging the drill hole before placing the explosives.
Although there were plenty of places to inspect, I zeroed in on a mine pillar on the south wall of the quarry which was dominated by purple fluorite (see photo 3).
One pocket I discovered was over a 30 cm in diameter, a 30 cm deep completely lined with 5mm – 1 cm cubes (see photo 4). There were numerous other pockets exposed, with primarily purple crystals of various sizes and luster.
The discovery was a pocket of gemmy purple fluorite with barite partially to completely covered with orangish-brown to yellowish-brown smithsonite in this pillar! I noticed a small fluorite lined opening, and opened it with a 3 pound sledge hammer and wide chisel. The smithsonite specimens are botryoidal or have small club-shaped crystals. They average 1mm in length and when they are not inter-grown, are typically doubly-terminated. Inter-grown crystals are quite interesting under low magnification. Some specimens and cleavages are “turkey-fat” color, a couple are chocolate brown and almost as lustrous as sphalerite!
The occurrence of smithsonite is particularly curious, since I have not recorded a single sphalerite crystal in all my years studying the Hastie’s property. The pocket was almost 3 feet in length and varied from a couple to 10 inches in thickness. Immediately below the pocket was an unusual area where the limestone had been leached away, leaving a porous, silicious rock in its place (see photo 5).
The paragenesis of this pocket seems to indicate the carbonate component came from the leached limestone below the pocket. The zinc must have migrated an unknown distance up-dip from the sphalerite source. The barite formed after the fluorite, and generally prior to the smithsonite. However some late-forming barite crystals smaller than 3 mm occur on the smithsonite. Photo 6 shows a closer view of the smithsonite pocket.
We collected specimens from nearly a foot across to thumbnail size, with a few micromount specimens, too. I immediately donated one fine specimen to the Clement Mineral Museum, another to Hal Noltimier. We ended up with seven or eight flats of smithsonite.
Above the smithsonite, Mark worked an area particularly rich in lustrous purple cubes (up to two inches across). Most of the specimens were so inter-grown, it was difficult to get any “knock-out” specimens (photo 7). In the adit on the far side of the pillar, I found a large pocket where a couple of nice lustrous yellow fluorite crystals and some small gemmy clear calcite were picked up (photo 8).
Ron Stubblefield collected a specimen with several late-forming tabular purple fluorite crystals perched on regular cubes. I found one like that associated with the smithsonite. Hal and Paula collected fluorite off the rock piles in the pit. One razor-shape crystal required him to dig into the first aid kit.
Our plans to visit Rosiclare and mine dumps on top of Spar Mountain did not pan out, so Mark and I stayed in the pit as late as was practical. We visited the large mine tunnel and gingerly explored the first 100 feet (see photo 9). Roof bolts were hanging like iron stalactites: the 45 to 50 years of weathering – combined with the blasting above – had knocked the loose rock down from the roof of the tunnel. A number of specimens were found in the loose rubble. One was a 17 cm long specimen with cubes up to 6 cm wide, but they are somewhat etched. I also carried out a 30 cm -long boulder consisting of a doubly terminated honey-brown scalenohedral calcite crystal, deep purple fluorite and smaller calcite parallel crystals in pockets. This is the largest calcite crystal I have personally collected from Cave in Rock area. While aesthetic, it is not a high-quality piece and was placed my rock garden.
Mark and I brought back 25 flats of specimens along with a bucket with ore samples for grab bags and fluorite cleavages to make octahedrons (photo 10) collected from other mine dumps. We cleaned and divided the specimens before he headed back home. At the last minute, I had used my clamshell luggage topper on his car to hold our camping gear. The last time I had been in a small car this fully-packed was on a cross country astronomy junket I did with a friend 20 years ago!
After an incident a couple of years ago the Hastie’s changed their property-access policy and do not want to deal with groups or collectors they do not already know. I have known the owners for 18 years (geez, that’s hard to believe!) and respect their wishes. This is an active quarry with huge equipment and dangerous areas not suitable for inexperienced collectors. I will have some material available, although it is possible that most will be sold or traded before the article is published. I am scheduling another trip later this year, but with the Hastie operations, there is no telling what areas will be accessible and what will be found!
Reference:
Goldstein, Alan, 1997. The Illinois-Kentucky Fluorite District, The Mineralogical Record, vol. 28, no. 1.