Sandstone
A sedimentary rock consisting of sand sized sized grains of quarts and feldspar, or older rocks cemented with silica, iron oxide or calcium carbonate often forming a muddy matrix. Sandstones vary greatly in color, texture of grains, composition, degree of cementation and layering. Deposits of sandstone are found on relatively flat surfaces and are stratified or bedded. In most cases, the stratification is parallel to the deposition surface, but subordinate layering may occur. Ripple marks and animal trails may appear on bedding surfaces.
Quartzite
A compact granular rock composed of quarts crystals, usually so firmly cemented as to make the mass homogenous. The stone is generally quarried in stratified layers, the surfaces of which are usually smooth, and the crushing and tensile strength are extremely high. The color range is wide. Typically a silver-gray, metamorphic sandstone formed in exceedingly hard layers. In some deposits, intrusion of minerals during the formation process create unusual shades of brown and gold.
Slate
A fine grained, hard, dense, low-grade metamorphic rock derived from clays, shale's and volcanic ash which possess a cleavage that permits it to split readily into thin, smooth sheets. This splitting, known as slaty cleavage, results from recrystallization under pressure and commonly develops at an angel to the bedding planes. Minerals present are quartz, sericite, chlorite, some graphite, titanium oxide and iron oxides. Shale is clay that has been subjected to high pressure until it has hardened rock like.
Granite
A very hard, crystalline, igneous rock, gray to pink in color, composed of feldspar, quartz, and lesser amounts of dark ferromagnesian materials. Black "granites" are similar to true "granites" in structure and texture, but are composed of different minerals. Gneiss, which is a metamorphic rock with a banded or coarsely foliated structure, is often called "Trade Granite." composed essentially of silicate minerals with interlocking and visibly granular texture which is due primarily to alternating layers, regular or irregular, of contrasting mineralogical composition.