Royal Green Marble Quarry (Warnes Quarry; Rock Products Company Quarry), Lopatcong Township, Warren County, New Jersey, USAi

Regional Level Types
Royal Green Marble Quarry (Warnes Quarry; Rock Products Company Quarry)	Quarry
Lopatcong Township	Township
Warren County	County
New Jersey	State
USA	Country

The Royal Green quarry was excavated in a band of Precambrian marble that outcrops on Marble Mountain. Marble Mountain, on the New Jersey side of the Delaware River, and its extension into Pennsylvania, Chestnut Hill, is the northwestern-most exposure of the granulite facies metamorphic rocks that underlie a range of highlands known as the Reading Prong. The marble in the Phillipsburg/Easton area is more dolomitic than that found further to the northeast. These rocks have not been precisely correlated with the Franklin Marble. However, as currently interpreted (Volkert, 2010) all the marble along the northwestern margin of the Reading Prong highlands represents a shelf sequence along the margin of a back arc basin. Therefore, the marble in the Easton quadrangle is, at least, broadly correlative with the Franklin Marble.

Peak metamorphism of the Reading Prong rocks occurred during the Ottawan phase of Grenville Orogeny, which by approximately 1030 Ma had begun to wane. For approximately 55 Ma following the emplacement of the post orogenic, undeformed Mount Eve Granite, at 1020 Ma, the Reading Prong rocks were intruded by pegmatites. The details of Reading Prong geology, more than this brief outline, are beyond the scope of this work. There is a voluminous literature concerning this subject and the reader is referred to Volkert et al. (2005), Volkert and Drake (1999) and the references therein.

The long period of pegmatite intrusion and hydrothermal activity has distinctly effected the granulite facies metamorphic rocks of the Reading Prong. Widely scattered U/Th + REE mineralization is associated with pegmatites and the marbles have been recrystallized to produce skarns with no metamorphic fabric (Volkert, et al, 2005). In the Easton, Pa. area the recrystallization of the dolomitic marble includes extensive conversion to serpentine.

At the Royal Green Quarry, as well as the better known Williams Quarry just down strike and across the river, pegmatites are abundant. Montgomery (1957) attributed the serpentinization, sulphides and uranium/REE mineralization to the post orogenic pegmatites and associated hydrothermal activity. At the Williams quarry fracturing was more pervasive and the thorian uraninite was altered to several secondary uranium and thorium species. At the Royal Green quarry late alteration of thorian uraninite was absent or minimal.