A quarry in the Jurassic Haycock Mountain diabase between Quakertown and Perkasie, northern Bucks County. The General Crushed Stone Corporation closed the operation more than 25 years ago because the stone was too heavy to compete with the carbonate rock aggregates, quarried abundantly a short distance to the north and the argillite aggregates that dominated the market to the south. The specific gravity of Rock Hill Quarry material was consistently around 3.05 verses 2.7 to 2.85 for competing sources. This means that a ton of Rock Hill stone was only 90 to 95% of the volume of material from their competitors. Its isolated location also resulted in longer average truck hauls.

In 2017 renewed activity began at the quarry, now owned by Hanson Aggregates. The operation has been leased to Richard E. Pierson Materials Corporation. The restart has been the object of the typical local opposition. As of late 2019 things are still in flux.

The diabase in the Rock Hill Quarry was cut by numerous albite-actinolite (Ab-Act) veins. The fracture fillings in these veins were nearly always massive and coarsely crystalline. Most of the veins were less than 3 inches wide but thicker examples were occasionally seen.

In the late 1970s, a vein was exposed on an upper bench in the west end of the quarry, just off an access road, that contained open space over a length of several yards. The vein contained white asbestiform amphibole, probably tremolite, and dense, matted amphibole (mountain leather). Also present were very light yellowish green, almost white, prehnite and dark green titanite. The titanite crystals are sharp and of the typical habit but not elongated.

A few other mineral species have been reported from veins in this quarry. However, with the exception of the massive Ab-Act vein and the single titanite-bearing occurrence, secondary minerals were very sparse.

Other Regions, Features and Areas containing this locality

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