Anthracite Mohs scale), its higher relative density of 1.3–1.4, and luster, which is often semi-metallic with a mildly brown reflection. It contains a high percentage of fixed carbon and a low percentage of volatile matter. It is also free from included soft or fibrous notches and does not soil the fingers when rubbed. Anthracitization is the transformation of bituminous coal into anthracite. The moisture content of fresh-mined anthracite generally is less than 15 percent. The heat content of anthracite ranges from 22 to 28 million Btu per short ton (26 to 33 MJ/kg) on a moist, mineral-matter-free basis. The heat content
A. L. A. Himmelwright coal fired furnace with radiators in each room for heat; a similarly stone built garage of sufficient size to accommodate two large touring cars; and awnings and shutters with a concrete sidewalk all around. The walls are of granite, the floors and ceilings of poured concrete with steel reinforcement, the roof is lined with copper. Woodwork, plaster, brickwork, and concrete were all specced to be of "first class materials and workmanship". Himmelwright estimated its lifespan at 400–500 years. In 1913 Himmelwright published detailed engineering plans, drawings, and instructions on how to build replicas of the Stone House in a book,