In my business of geological education, I meet a lot of people in different geographic areas. That is probably one of my most favorite things about doing what I do, you hear various stories related to the area’s geology, see new faces and share your interest with them. Sometimes, during one of our visits to a town to do a program, we luck out and learn something very interesting about the area, probably something I never heard before and the folks have the evidence to proof what they are talking about.
One of those case recently arose. I had met a gentleman who is very interested in local minerals and has indeed discovered some “cool” stuff on his expeditions in the YorkCounty. One of his great pieces is petrified wood from Manchester. Well preserved and rather large for a specimen, I must have looked like a dog waiting for my supper when you showed me that one!! Certainly one of the best pieces of local petrified wood I have seen from YorkCounty. Not to get off track, this person had a friend from the Newville, CumberlandCounty area who has done his own research of that area. With his research he had some questions about items he recovered from the GreatValley region of central Pennsylvania. So we made arrangements to meet on a Sunday afternoon since that was the only time I had available in the next few weeks and off we go to the Newville area.
I have done very little research in the GreatValley but had time to do some preliminary reading on maybe I should expect to find out there. I studied the geologic maps since this person gave me an address to check out including Goggle Earth to get a picture of the lay of the land. With hammer and camera in hand, we met at the designated location (thanks to the GPS) and he gives me some background of what he is doing and has found. It turns out that much of his research is not geologically related but archaeologically based and certainly I still felt comfortable in that realm.
During the preliminary discussion, I was told what my goal was for the day. In the rolling hills of the western GreatValley area, this friend uncovered hundreds of small six-sided shaped quartz crystals almost resembling the famous Herkimer diamonds from upper New York state. Wow, what I had to decide was if these crystals were really transported in from Herkimer for some sort of trading goods from previous residents of the valley or were rthey native to that area?
Again, I did not have much experience of mineral collecting from this portion of CumberlandCounty but I think I would have heard about these clear quartz crystals. I should have seen some of these crystals for sale at a local rock and mineral show or even a rock swap, but I never did. After he took me to an area where you has unearthed many of these crystals, I soon drew a conclusion that these crystals were native, weathering out of the limestone. Wow, so cool and just walking through the freshly dug excavation, these crystals were abundant. My guide and his friend even have perfected finding these at night using flaahlights at a low angle to the ground to detect their reflection. Very creative!!!!
I wanted to see more of the immediate area to look at the available rock exposures and loose rocks in the fields. Upon walking more of the property, I was shown a cave with a vertical entrance which apparently has been known by local cavers for many years. I knew I was in sinkhole and cavern area knowing the rock formations for which laid under my feet. Sure enough, with the topography, I located a solution valley that was created when two of more sinkholes combined to make one large sink and later became inactive, forming a narrow, elongated valley. Other sinkholes were spotted around the edge of this property where residents brought their old metal and disposed of it in the sink.
Our last stop was at a small inactive quarry where the limestone was well exposed. A great outcrop to see the structure of the limestone and maybe some more quartz crystals. Although we didn’t find any of the clear quartz crystals, we did locate a cavity of white quartz crystals. No other minerals were detected but seeing these clear quartz crystals native to the limestone and having great fellowship with my guides for the day was certainly worth the trip.
After I got home and knowing exactly where I was on the trip, I went to my library again to find out if these fine quartz crystals were every reported by a geologist. Sure enough, when I went to the classic book “Mineralogy of Pennsylvania” by Samuel Gordon in 1922 and I turned to CumberlandCounty, what did I see? Not one listing of clear quartz crystals but two in the county. After locating these locations on the CumberlandCounty map and referring to the geologic maps, both of those locations were in the same limestone formation as I visited earlier. It is hard to believe that among my rockhounding friends that have explored CumberlandCounty, they never said a word about the quartz.Read More