Equipped for large-scale production
The stone, which has also been known as "Gem Mist" in the memorial market, is now being marketed as American Black granite. The granite, while similar in appearance to Jet Mist granite from Virginia when cut against the grain, has a much darker tone and more pronounced veining when cut in the proper direction.
Since taking over the quarry, Rock of Ages has introduced the stone to the Italian market and the German memorial industry, but 90% is still sold in the U.S. "As a traditional monument stone, it commands a higher price here [than overseas]," said Robert Campo of Rock of Ages, adding that the once over-abundance of Jet Mist in the international marketplace had lowered the selling price for these types of black granite in the building market abroad. However, he said that as customers discover the darker background and pronounced veining of American Black, the material is making some important inroads in the international architectural market. In a recent example of this, the company supplied over 150 cubic meters of material for a prestigious project in France.
Quarrying operationsWith 12 workers, the quarry produces between 200 and 250 cubic meters of material per month. The quarry operates one shift 12 months per year, and the material recovery rate currently stands at about 15%. "As we develop the quarry, the recovery should get better as we get deeper into the thicker granite beds," Campo said.
Equipment in the quarry includes Tamrock drilling equipment, which was recently purchased, and Pellegrini diamond wire saws. During Stone World's visit to the quarry, five different drilling rigs were in operation at the same time. Campo explained that representatives from Rock of Ages have worked directly with the engineers from Tamrock's plant in Finland to help in developing drilling equipment that is suited for the specific characteristics of their quarries.
The Pellegrini wire saws are also utilized for maximum efficiency in the quarry, as they cut vertically as well as horizontally. A typical block size is 6 to 10 feet long x 5 feet wide x 3 to 6 feet high. "We try to get gangsaw blocks whenever possible," Campo said. Blocks and rubble stone are maneuvered with loading equipment from Hitachi.
At the cutting mill, the blocks are processed on either a Pellegrini wire saw or a 3-meter block saw. The blocks are trimmed, and the company also produces thick slabs for memorials. Unlike the old ownership, however, Rock of Ages primary objective is to market the material in block form.