Hobbies And Interests
Limestone
A sedimentary rock composed principally of calcite or dolomite, limestone has long been in demand among builders -- for instance, the Great Pyramid of Giza, in Egypt, is composed entirely of limestone -- for its texture and beauty, as is its close relative, marble. Although limestone is very durable, it is a relatively porous rock and especially vulnerable to weathering due to acid rains. Fossils are often found in limestone.
Granite
Granite is an igneous rock composed of silicates, feldspar and, most importantly, quartz. Because it is an especially hard stone, granite is used for curbing, building and paving. Also, because it comes in many colors and patterns and polishes beautifully, granite is a popular choice for counter tops, fireplace mantels and memorial headstones.
Sandstone
When sand-sized particles of minerals -- most typically quartz -- accumulate over vast reaches of time and are then compacted under enormous pressure for an even longer time, the result is sandstone. An important building and paving material, sandstone resists weathering and is relatively easy to work.
Sand and Gravel
Their humble station notwithstanding, sand and gravel are indispensable elements of everyday life. Also known as "aggregate," sand and gravel are used for making concrete, asphalt and bricks. They are found in construction fills and are spread on icy roads during winter. The United States is both the leading producer and consumer of sand and gravel.