Stone Quarries

• Natural stone is not usually mined like coal or metals, it is quarried. Quarries are large, open-pit mines dug to uncover shelves of rock. The rock is broken down into manageable sizes and transported to workers who shape and cut the rock into the forms for selling. Stone quarries can be enormous--the world's largest, located in Vermont, is almost 600 feet deep. Quarry workers use explosive blasts or high-pressured bursts of air to shear through the rock, and mechanical chisels and sledgehammers to break it into smaller chunks.
  
  

Marble

• Marble is one of the most popular natural rocks. It is prized for its rich color and decorative value, but there are many kinds of marble. Any calcareous rock that is formed in nature and can be polished is considered a marble. Marble is classified by soundness, and the four different categories--A, B, C and D--determine how marble should be properly fabricated to be ready for use.
  
  

Granite

• Granite is also a very popular stone, used especially as a building material because of its density and resistance to weathering. Eighty-three percent of modern monuments are granite. Granite is formed from feldspar and quartz, with other minerals occasionally mixed in. It is graded by its grain, which is determined by the size of the feldspar crystals present in the granite. Fine-grain granite has feldspar crystals that are an eighth of an inch or less, while coarse-grain granite is composed of crystals around half an inch.
  
  

Limestone

• Limestone is a sedimentary rock that is commonly used for building. Many of the buildings in the United States are made from limestone, as are the Great Pyramids. Limestone is made up mostly of a mineral called calcite, which comes from the remains of clams, coral and other shellfish. Limestone is the number one source of lime for cements, which are the most important building materials in modern society.
  
  

Slate

• Slate is a metamorphic rock that is mainly composed of quartz and muscovite, with various other minerals in small amounts. Slate is most famous for its use as a roofing material, but for centuries slate was used as a writing tool along with chalk. It is still in popular use as a material for countertops, billiards table tops and as a medium for artists.