National Limestone Quarry, Mount Pleasant Mills, PA
We have been invited by the Gem, Lapidary and
Mineral Society of
Montgomery County, Maryland, to join them on a field collecting trip to
the National Limestone Quarry, Mount Pleasant Mills, PA on
O ctober 29, 2016.
ctober 29, 2016.
We've now been to the MPM quarry twice in the past 2 years and have had fantastic collecting for wavellite up on the sandstone ridge. And those with a good eye for invertebrate fossils have done very well also. Getting the really great wavellite requires some major digging but it's well worth it. We've also done well on both calcite and fluorite down in the main quarry. Last spring a few of us went over to the Middleburg Quarry for a short exploratory visit. We easily found abundant calcite, fluorite and cave formation rock. If I were going on this trip I would want to spend my entire day at Middleburg (having already gotten super wavellite specimens). But I will not be on this trip. I will select a DMS Group leader from those who sign up. I will take care of getting the co-insurance and any other paperwork.
Read the invitation below. And you MUST reply to Jonathan Harris by email that you accept and agree to abide by the Rules and Guidelines, and the waiver of liability. Please respond to me if you wish to participate in the trip. I'll forward attendees names to Jonathan a week or so before the trip. Finally, Bill Stephens is going to dedicate a meeting to discuss the geology and mineralogy of wavellite at this site at our November 9 meeting.
Here is the invitation from Jonathan Harris On Saturday September 26, we have a field-trip opportunity to collect at the National Limestone Quarry at Mt. Pleasant Mills . If there is sufficient interest, then it is likely we can all go to the nearby Middleburg Quarry. This is a great site for wavellite, strontianite, fluorite (purple masses) and more recently varascite and turquoise. Collectors should bring a specimen from some other location for Eric Stahl, the manager of National Limestone Quarry. If the operator blasts in certain sections, celestite and sphalerite might also be found.
The trip will start at 9am at the quarry office. Mt. Pleasant Mills is about 3-3.5 hours away, but it is worth it! Children are permitted 10 and older, but a parent must stay near and supervise their children and leave the quarry with them if they get too restless to be safe. We can accommodate members of the Delaware, Northern Virginia, and Southern Maryland clubs on this. Those interested in the wavellite should bring good digging equipment.
Please RSVP by the Wednesday before the trip. Quarries are now often requesting that we have a minimum number of people so that their employees' time will be used effectively. Thus it is important that people who sign up on these and other trips attend.
Please respond to me by email (email@example.com) if you wish to join this trip. If I don't confirm your sign-up by email in a few days, email me again. Specific details will be sent to those who sign up a week or so before the trip.
Here's a trip report by Joseph Bytella that pretty much tells what we can expect at this site. This article may be found at http://www.smrmc.org/uploads/3/4/4/8/3448020/10-10-02_-_national_limestone_quarry_pa.pdf
Trip Report for National Limestone Quarry in Mount Pleasant Mills, PA
By Joseph Bytella
The Southern Maryland Rock and Mineral Club conducted a field trip to the National Limestone Quarry in Mount Pleasant Mills, Pennsylvania on Saturday Oct. 2, 2010. Dave Lines was the trip coordinator and leader. The field trip was attended by nine of our club members and five members from the Northern Virginia Club.
Dave greeted the attendees at the quarry entrance between 9:00 – 9:30 AM, then we were briefed by the Eric Stahl (quarry owner) in a field trailer about safety procedures and the minerals typically encountered in the quarry, e.g., wavellite, calcite and strontianite. Wavellite is a rare mineral (Al3[(OH,F)3(PO4)].5H2O), whose only other noted location in the United States is in the state of Arkansas.
After the safety briefing, most of the group members mined a loose outcrop of wavellite in a coarse sandstone matrix. Sledge hammer and chisel were required to expose the small green veins of wavellite. Most of the mineral specimen crystals were only 1 to 2 mm in diameter.
Later in the day, we mined the loose limestone boulders in another location in the quarry and found numerous pockets of calcite crystals, and some pockets yielded rare double-terminated calcite crystals. A few club members found fossilized coral and brachiopods in the excavated limestone boulders which originated from the Silurian and Devonian eras.
The wavellite deposit is not in the main quarry --- rather, it is located in a tiny outcrop on the backside near the top of the mountain (ridge) where the quarry is. Accessible only by a very narrow road which had been bulldozed along a steep mountainside, the wavellite "pit" is a half moon shaped affair that appears to have been scooped out with a frontend loader or a dozer for about 50 feet long and 20-30 feet back into the mountain. The back side is sloped about 45 degrees. The matrix is weathered sandstone/limestone with some visible fossils such as moonsnail gastropods. The highly fractured matrix is interspersed with red clay and red dirt.
The wavellite is generally in thin veins in the rock and seemed to be covered with and/or stained by the red mud. Since the area had received a deluge of 8 inches of rain the day before, the rocks on the surface were washed clean. Pale yellow-green wavellite was readily visible on at least 1% of the matrix in the form of little half-spheres ranging from 1/8 to 3/8 inches in diameter. The key to finding more wavellite (after the easy stuff was picked up) was to scrub (with a stiff brush) the mud from each and every surface of the rock matrix pieces in a bucket of water --- and to look for the shape --- round half spheres --- of the wavellite. (Note: At home, Super Iron Out seemed to remove most of the red/brown stain from the wavellite.)
About ten of the attendees worked the wavellite pit for a few hours, then all but three moved back to the main quarry. The three who remained stayed until 2:30 p.m. and were able to search more carefully and safely use sledges and chisels to split open any yellow-green seams of the wavellite. They were sometimes rewarded with pockets of red mud which covered the wavellite spheres. Some of the pockets also contained small quartz crystals interspersed with the wavellite.
The best wavellite specimen I saw was a plate about 3 inches by 4 inches covered with ¼ inch green wavellite spheres and it was found on the mountainside below the pit in thick brush.