Rocks make up all of the material of the landmasses of Earth and are defined as an aggregate of minerals and silicates and is predominantly found in the solid state of matter. Rocks are split into separate categories such as sedimentary and igneous which define the way they were created or formed. Rock allows for the building of structures through the use of concrete,bricks, stucco, and a myriad of other uses. In addition, rocks also comprise the crystals formed such as salts and precious gemstones like diamonds and sapphires. Some rocks are formed from the decay of organic materials as in the case of coal and peat. Even clocks use rocks in the form of quartz for their time keeping. Rocks will typically have more generic names like boulder, stone,pebble and mountain and do not usually have proper names such as copper or basalt.
By definition minerals are naturally occurring substance made from geological processes that possess a characteristic chemical composition, a particular atomic structure and specific properties. Minerals can be anything from salt to aluminum and encompass a wide range of materials. Minerals allow for every industry to function and flourish in today's economy and are used in industries like road construction, building, medical remedies and skin care as well as defense and automobile production. A basic difference between rocks and minerals is that rocks are made up of two or more minerals but minerals are not made up of rocks. All minerals have proper names like aluminum and gallium and are formed by very specific processes.
Rocks are formed in one of three processes within the Earth;sedimentary, igneous and metamorphic. Sedimentary rocks are formed from the deposits of erosion by air and water as well as loose soil that has been compacted over long tacks of time and under pressure. Sandstone and limestone are commonly used sedimentary rocks. Igneous rocks are formed from heat and can be created above or below the ground via volcanic processes. As magma is cooled underground or lava cools on the surface igneous rocks are formed. There are four kinds of igneous rock called granite, scoria, pumice and obsidian. Metamorphic rocks are formed form other rocks changing or morphing into another type of rock. Through years of heat and pressure rocks change properties and forms into metamorphic rocks; examples are things like diamonds and coal. There are two types of metamorphic rocks called schist and gneiss.
Some minerals and rocks exhibit unique and special properties that have been used by humans for centuries and some are just plain fun. Fluorescence is a property of some minerals that contain atoms that absorb ultraviolet light. This light is then emitted in the form of visible light that humans can see and in some instances it seems to glow. Another similar effect is that of phosphorescence. This is caused by atoms in the mineral that hold the extra energy of light for some time after being "charged" with light. The Glowing numbers on a watch are caused by phosphorescence. Minerals like quartz are able to pulse when electricity is applied to them. They have been used as time keeping devices for centuries and are typically crystalline in nature.Depending upon the crystal the timing or pulses change and can be kept to a steady beat.
Certain kinds of rocks and minerals, such as gemstones, are highly prized when polished and cut. Gemstones are defined as a piece of rock or mineral that when polished is used in art and wholesale jewelry. A small circular saw is used to cut the gem into an approximate shape and is then taken to a grinder. In some instances the gems are tapped with a hammer to free loose bits of stone. Progressively the grinder used will have smaller and smaller grit to perform finer detailed cuts and facets of the stone. After the cutting has been approved and finished the polishing is performed. When finer abrasives are used the process is called sanding. Very fine grades of diamond grit are used to polish, and cut, the stone to a mirror shine and remove the marks of the cutting and grinding process.
An interesting gemstone is amber which is formed from the fossilized tree sap of ancient trees. As a general rule of thumb amber is typically 300 to360 million years old and is found in some large deposits around the world.Truly rare amber contains insects and or organisms that have been fossilized in the amber. Although these specimens are rare many have been found are extremely expensive. Amber ranges in color from a deep golden brown to a very light lemon yellow color. Amber is a soft mineral and can be easily scratched which is why jewelers reconstitute it to make it stronger.
Crystals are formed through a specific process that enables them to grow in a specific structure or shape. The shape and structure are determined by the chemical composition of the crystal in question. Many of the Earth's crystals where formed millions of years ago due to high heat and pressure,but crystals can form when a gap or hole allows water or liquid to seep in and develop under pressure. The liquid brings in minerals that are deposited when the liquid evaporates and leaves the minerals behind. Most minerals take thousands of years to develop while others, such as salt, can be seen growing right before an observer's eyes.
Rocks and minerals supply humans with utilities, art, jewelry, and building materials; from the aesthetics of diamond, gold, and silver jewelry to the necessities of concrete, brick, and asphalt. Most importantly, without rock the Earth would not exist.