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Review of Related Literature
Chalk is a type of limestone. Air and water do not wear chalk away easily, so when chalk is next to the sea, it often makes a largecliff. The "White Cliffs of Dover" in Kent, England are a good example of this. When chalk is near the top of the ground, it often makes chalk hills. Chalk holds water, so these chalk hills have a lot of water in them, and when the weather is very dry, water comes slowly from the chalk. Chalk is mostly formed from the calcareous (CaCO3) skeletons of countless tiny planktonic algaecalled coccoliths. It was laid down in the Upper Cretaceous period. Chalk can write on a chalk Board.
Blackboard chalk is not real chalk. It is really gypsum (calcium sulfate), but often people call it "chalk". People use it for drawing on hard things, because it is soft. If this chalk is rubbed on something hard or rough, it will leave a mark. People often write with chalk on a chalkboard or blackboard. A chalk eraser or water can be used to clean the chalk marks away so the board is blankagain. Shops usually sell blackboard chalk in sticks that are about 5 cm long.
The main component of chalk is calcium carbonate (CaCO 3 ), a form of limestone. Limestone deposits develop as coccoliths (minute calcareous plates created by the decomposition of plankton skeletons) accumulate, forming sedimentary layers. Plankton, a tiny marine organism, concentrates the calcium found naturally in seawater from .04 percent to 40 percent, which is then precipitated when the plankton dies.
To make chalk, limestone is first quarried, generally by an open pit quarry method. Next, the limestone must be crushed. Primary crushing, such as in a jaw crusher, breaks down large boulders; secondary crushing pulverizes smaller chunks into pebbles. The limestone is then wet-milled with water in a ball mill—a rotating steel drum with steel balls inside to further pulverize the chalk. This step washes away impurities and leaves a fine powder.
The base of
Chalk is a type of limestone. Air and water do not wear chalk away easily, so when chalk is next to the sea, it often makes a largecliff. The "White Cliffs of Dover" in Kent, England are a good example of this. When chalk is near the top of the ground, it often makes chalk hills. Chalk holds water, so these chalk hills have a lot of water in them, and when the weather is very dry, water comes slowly from the chalk. Chalk is mostly formed from the calcareous (CaCO3) skeletons of countless tiny planktonic algaecalled coccoliths. It was laid down in the Upper Cretaceous period. Chalk can write on a chalk Board.
Blackboard chalk is not real chalk. It is really gypsum (calcium sulfate), but often people call it "chalk". People use it for drawing on hard things, because it is soft. If this chalk is rubbed on something hard or rough, it will leave a mark. People often write with chalk on a chalkboard or blackboard. A chalk eraser or water can be used to clean the chalk marks away so the board is blankagain. Shops usually sell blackboard chalk in sticks that are about 5 cm long.
The main component of chalk is calcium carbonate (CaCO 3 ), a form of limestone. Limestone deposits develop as coccoliths (minute calcareous plates created by the decomposition of plankton skeletons) accumulate, forming sedimentary layers. Plankton, a tiny marine organism, concentrates the calcium found naturally in seawater from .04 percent to 40 percent, which is then precipitated when the plankton dies.
To make chalk, limestone is first quarried, generally by an open pit quarry method. Next, the limestone must be crushed. Primary crushing, such as in a jaw crusher, breaks down large boulders; secondary crushing pulverizes smaller chunks into pebbles. The limestone is then wet-milled with water in a ball mill—a rotating steel drum with steel balls inside to further pulverize the chalk. This step washes away impurities and leaves a fine powder.
The base of