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                                                        Kurtz Quarry

                           (Martin Limestone)

                            Denver, PA

 

November 20, 2004, Saturday: Martin Limestone Kurtz Quarry, Denver, Lancaster Co., PA:  This was the first DMS trip into this active quarry in a number of years.  This quarry cuts through dense gray to black dolomitic limestone.  Mineralization occurs as vein fillings in brecciated limestone.   Minerals reported to have been found at this quarry include: pink and white varieties of dolomite, small calcite crystals, dark purple fluorite cubes, minute sphalerite crystals, yellow barite on pink dolomite, quartz crystals, chalcopyrite, pyrite and malachite.

 

Kurtz Quarry Fieldtrip Slide Show, 11-20-2004 (IE)

Kurtz Quarry Fieldtrip Slide Show, 11-20-2004 (N)

 

Out in the Field

Bob Asreen

Martin Limestone Kurtz Quarry, Denver, PA - November 20, 2004

On November 20, 2004, 11 mineral collectors braved the inclement weather and visited the Kurtz Quarry in Denver.  This also was the first DMS trip into this active quarry in a number of years.  This quarry cuts through dense gray to black dolomitic limestone of the Lower to Middle Ordovician aged Epler Formation and the Middle Cambrian Buffalo Springs Formation with mineralization occurring as vein fillings in brecciated limestone. 

The collecting group included 10 DMS members (Joe Meloney, Ken Casey, Tim Cretien, John Osoinach, Karissa Hendershot, Guy and Wendy Sbriglia, Eric Hottenstein and his son Jake, and yours truly) along with Jim Schoonmacker from the MGS.

The most notable find of the day was again made by Joe Meloney, whose large plate of calcite crystals sprinkled with pink saddle dolomite crystals, purple fluorite cubes and micro pyrite is pictured on the DMS web site.

We all came out of the quarry with slabs containing calcite crystals, pink saddle dolomite crystals, fluorite cubes, and veined chalcopyrite and/or pyrite.

Geology

The A.G. Kurtz quarry is located at the northern boundary of the Lancaster Valley Section of the Piedmont Physiographic Province. The Lancaster Valley consists of Cambrian- and Ordovician-aged limestone and dolomites of varying thickness that have been faulted and folded. Immediately bounding the quarry to the north are Triassic-aged red beds, composed of conglomerates, sandstones and shales, some of which are exposed along Denver Road.

The two rock units that are exposed in the quarry are the Lower to Middle Ordovician aged (485 million year old) Epler Formation and the Middle Cambrian (520 million year old) Buffalo Springs Formation.

 

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Deformations Quarry overview Slick-n-slide

Geologic Time Scale

The Epler Formation consists of dark gray to black, very finely crystalline, interbedded limestone and dolomite, which is exposed in the northern 4/5 of the quarry. The Buffalo Springs Formation, which is exposed only in the previously mined cove along the southern highwall, is a light to dark gray, fine to medium crystalline, laminated and interbedded limestone and dolomite.

The rocks at Kurtz Quarry were intensely deformed from faulting and folding. A high thrust fault (dipping approximately 70 degrees south), with a displacement of a few thousand, separates the Buffalo Springs Formation in the southern part of the quarry from the Epler Formation in the north. The rocks in the Epler Formation are not as intensely deformed as those in the Buffalo Springs Formation. However, the Epler Formation is steeply dipping at the fault, is cut by several faults with resultant fold development and dips approximately 15 to 20 degrees at the northern highwall.


Mineralogy

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Pink Dolomite Pyrite vein



Mineralization occurs in veins and in vug fillings in brecciated rock and includes:

Barite, which is rarely found as yellowish plates (5mm);

Calcite, which commonly occurs as massive white veins and scalenohedral crystals and smaller colorless crystals;

Chalcopyrite, which occasionally occurs as golden crystals on and in the calcite;

Dolomite, which occurs as well formed, pink curved crystals usually associated with calcite and fluorite;

Fluorite, which occurs as 3-4mm purple cubes or seen as purple sheen on fractures and joints;

Malachite, which appears as a green halo around chalcopyrite;

Pyrite, which is common as tiny pyritohedron forms associated with calcite and fluorite and as inch cubes in the green mudstone/limestone layer;

Quartz, which occurs as opaque masses in calcite and occasionally as terminated clear crystals; and

Sphalerite, which is uncommon but sometimes occurs as red-orange masses associated with calcite and dolomite. [Bob Asreen]

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