The purpose of the Harrisburg Area Geological Society (HAGS) is to stimulate geologic thought, advance and disseminate geologic knowledge, and provide fellowship amongst area individuals interested in earth sciences. Monthly meetings (at GTS Technologies at 441 Friendship Road in Harrisburg) present a realm of geologic topics, ranging from tectonics, coal, carbonate groundwater geochemistry, Martian geomorphology, engineering geophysics, nuclear waste repositories, and ore mineralogy. Field trips allowed members to visit geologic sites within and beyond Pennsylvania. All events are open to the public and free unless otherwise stated. Meetings are at GTS Technologies, 441 Friendship Rd, Harrisburg, PA 17111. They occur at 6:30 PM on the second Thursday of the month, except summer months.
The Grace Mine in New Morgan Borough, Berks County, Pennsylvania
Presented by: Ron Sloto, P.G., West Chester University
Meeting Date: Thursday, October 10, 2019
Meeting Time: 6:30 p.m.
Meeting Location: AEG Offices 441 Friendship Road (near Bass Pro Shop)
Dinner Location: Fiesta Mexico 3957 Paxton Street, Harrisburg
Dinner Time: beginning at 4:45 or whenever you get there
Presentation Summary: The Grace mine is unique among the Cornwall-type iron ore deposits in Pennsylvania. It is the only mine to exploit a Cornwall-type iron ore deposit with no surface expression. The Grace mine orebody was the first mineral deposit to be discovered by an airborne magnetometer survey. The survey, conducted in 1948, consisted of 7,000 linear miles of flight lines spaced 0.25 mile apart extending from the Delaware River on the east to Gettysburg on the west. The first core drilling rig arrived at the site on September 1, 1949. It struck the orebody at a depth of 1,524 feet. The sinking of two shafts was begun in 1952. In 1955, shaft A reached a final depth of 2,208 feet, and shaft B reached a final depth of 3,079 feet. Production began in 1958. The processing plant produced iron ore pellets about 3/8 to 5/8 inch in diameter averaging 65 percent iron. Pyrite containing cobalt and copper was recovered by flotation. Cobalt concentrates were produced as early as 1961. The Grace mine closed in 1977; however, the ore body was not exhausted. At the time of closure, a zone of ore 480 feet thick and rich in copper had been outlined by drilling to the northeast. A total of 45 million tons of crude ore was produced at the mine. Most of the mine dumps were crushed and used for aggregate and in highway construction.
The Grace mine orebody occurs at the contact between diabase and Cambrian carbonate rock along the southern border of the Mesozoic basin. The bedrock in the vicinity of the mine includes Triassic-age shale, sandstone, quartzite, and conglomerate and Cambrian carbonate rock. These rocks were intruded by diabase varying in thickness from a few feet to 1,200 feet. The ore body is a replacement of Cambrian carbonate rocks of the Buffalo Springs Formation. The Grace mine deposit is a single ore body that is roughly tabular in shape, approximately 3,500 feet long, 700 to 1,500 feet wide, and 22 to 425 feet thick. It lies between 600 and 2,200 feet below sea level. The ore body contained about 118 million tons of ore. The Grace mine produced 51 different mineral species. It is best known for world-class specimens of magnetite and pyrrhotite. It also is known for the occurrence of the rare mineral tochilinite.
Speaker Bio: Ron Sloto retired from the U.S. Geological Survey in January 2015 after a 41-year career that included publication of over 80 reports, journal articles, and abstracts. Since that time, he has been on the research faculty at West Chester University. In addition to conducting research on the mineralogy of southeastern Pennsylvania, he serves as the curator of the West Chester University mineral collection and is the director of the West Chester University Geology Museum. Ron has been a mineral collector since the age of 5 and also has a keen interest in mining history. He has been working on a series of books describing county mining history and mineralogy. So far he has published the mining history and mineralogy of Berks, Chester, and Montgomery Counties. His current project is Bucks County.
Fall 2019 HAGS/AEG meeting dates and topics:
September 12, 2019 – Bill Kochanov, P.G., PA Geological Survey (retired) – see info above
October 10, 2019 – Ron Sloto, USGS and West Chester University – Grace Mine, Berks County
November 14, 2019 – Mark Eisner, P.G., Vice-President, Barton & Loguidice, D.P.C. – Challenges of Source Water Protection: How One Municipality Balances Economics and Public Health Interests
Spring 2020 HAGS/AEG meeting dates and topics:
January 9, 2020 – Gary Fleeger, P.G., PA Geological Survey (retired) – Finding a New Water Supply for Moraine State Park
February 13, 2020 – Pierre MaCoy, P.G., Susquehanna River Basin Commission – Making Abandoned Quarries Useful Again
March 12, 2020 – Larry Smith, P.G., PA DEP - Pennsylvanian Subperiod plant fossils
April 9, 2020 – Steven Jasinski, PhD, Paleontologist, PA State Museum – topic to be announced
May 14, 2020 – Professor Marcus M. Key, Jr., PhD, P.G., Dickinson College - An historical geoarchaeological approach to sourcing an 18th century building stone: Use of Aquia Creek Sandstone in Christ Church, Lancaster County, Virginia
HAGS Guidebooks, available for purchase, $5 each, plus $2 S&H. Multiple books may have discounted shipping.
1st Annual Field Trip‐Geology in the South Mountain area, Pennsylvania, Noel Potter, Jr., editor, April 24, 1982, Reprinted 1992. 37 p. $5.00 plus $2.00 S&H.
2nd Annual Field Trip‐ Geology along the Susquehanna River, south‐central Pennsylvania, J. Ronald Mowery, editor, April 16, 1983, 55 p. $5.00 plus $2.00 S8H.
3rd Annual Field Trip‐ Stratigraphy, structural style, and economic geology of the York‐Hanover Valley, G. Robert Ganis and David Hopkins, April 28,1984, 51 p. $5.00 plus $2.00 S&H.
4th Annual Field Trip‐ Pennsylvania’s polygenetic landscape, William D. Sevon, April 27, 1985, Reprinted 1992, 55 p. $5.00 plus $2.00 S&H.
5th Annual Field Trip‐ Selected geology of Dauphin and Northumberland Counties, Pennsylvania, by W. D. Sevon, W. E. Edmunds, G. R. Ganis, and J. P. Wilshusen, May 17, 1986, 22 p. $5.00 plus $2.00 S&H.
6th Annual Field Trip‐ Lower Jurassic diabase and the Battle of Gettysburg, D. T. Hoff, J. R. Mowery, and G. R. Ganis, April 25, 1987,17 p. plus appendices. $5.00 plus $2.00 S&H.
7th Annual Field Trip‐ The geology of the Lower Susquehanna River area, a new look at some old answers, Glenn H. Thompson, Jr., editor, May 7,1988, 56 p. $5.00 plus $2.00 S&H.
8th Annual Field Trip‐ Karst development and environmental geology in the carbonate rocks of the Lehigh and Lebanon Valleys, William E. Kochanov, April 29, 1989, 33 p. $5.00 plus $2.00 S&H.
In cooperation with the 20th annual Binghamton Geomorphology Symposium at Dickinson College‐The rivers and valleys of Pennsylvania, then and now, by William D. Sevon, October 20, 1989, 59 p. $5.00 plus $2.00 S&H.
10th Annual Field Trip‐ The Ridge and Valley Physiographic Province and the East Broad Top Railroad, William D. Sevon, June 1, 1991, 24 p. $5.00 plus $2.00 S&H.
11th Annual Field Trip‐ Paleozoic geology of the Paw Paw‐Hancock area of Maryland and West Virginia, Marcus M. Key and Noel Potter, Jr., May 9,1992, 25 p. $5.00 plus $2.00 S&H.
12th Annual Field Trip‐ South Mountain and the Triassic in Adams County, Pennsylvania, Raymond Britcher, editor, May 22, 1993, 41 p. $5.00 plus $2.00 S&H.
13th Annual Field Trip‐ Geology of the Lebanon Valley and western end of the Reading Prong, Charles Scharnberger, editor, April 23. 1994, 68 p. $5.00 plus $2.00 S&H.
15th Annual Field Trip‐ Pseudo‐Morainic Topography of the Allentown Area of Eastern Pennsylvania, Duane D. Braun and William E. Kochanov, May 4, 1996, 28 p. $5.00 plus $2.00 S&H.
16th Annual Field Trip‐ Notes on the Hamburg Klippe: biostratigraphy, ash layers, olistostromes, and “exotics,” G. Robert Ganis, April 26, 1997, 52 p. $5.00 plus $2.00 S&H.
17th Annual Field Trip‐ Geomorphology in the Northern Cumberland Valley, PA, including the Carlisle Deluge of 1779, Noel Potter, Jr., Donald Hartman, and Helen Delano, April 18, 1998, 49 p, $5.00 plus $2.00 S&H.
18th Annual Field Trip‐ The Cove Syncline by canoe, William M. Roman and Michael A. Knight, May 15, 1999, 16 p. plus maps, Out of Print
19th Annual Field Trip‐ Geology of the Kishacoquillas Valley and vicinity, Mifflin County, Pennsylvania, Michael A. Knight and William M. Roman, May 20, 2000, 18 p. plus maps and sections, $5.00 plus $2.00 S&H.
20th Field Trip‐ Geology and Geomorphology of the South Mountain Area, Cumberland and Franklin Counties, Pennsylvania, Noel Potter, Jr., and William D. Sevon, May 14, 2011, 64 p., $5.00 plus $2.00 S&H.
21st Field Trip‐ Shermans Creek from Dellville to Duncannon, Perry County, Pennsylvania, William Roman, May 12, 2012, 48 pages, color, $5.00 plus $2.00 S&H.
22nd Field Trip‐ Some geological aspects of the north side of the Cumebrland Valley in Cumberland County, PA, Bill Sevon, May 4, 2013, 33 pages, large font, color photos, $5.00 plus $2.00 S&H. No formal guidebooks were prepared for the 9th (1990) and 14th (1995) Field Trips. The 2001 trip was a repeat of the 2000 trip.