Page 34 - Curriculum Visions Dynamic Book

 Whalebone is rich in calcium.This figure of an Inuit hunter is carved from fossilised whalebone.The people of Pangnirtung, Baffin Island, found that
the hard texture of fossilised whalebone provided a good alternative to soapstone, the traditional Inuit carving material.
 Calcium rapidly reacts with oxygen in the air to form a protective (dull) oxide coating that tends to prevent any further reaction. It only looks silvery when freshly cut.
eroded in unique ways.They include the formation of underground tunnels and caverns and the growth of stalactites and stalagmites. Many limestones are a mixture of the remains of the skeletons of animals and mud.The type of limestone is often named after the most common fossil, for example, shelly limestone for the large number of fossil clam shells found in it.
Biology
Calcium is an essential part of all animal cell walls. It is found in leaves, bones, teeth and shells, often as calcium phosphate. Calcium helps in blood clotting.
Calcium is harmless, and extra calcium is recommended for people as they become older to help ensure they guard against the risk of bone loss.
 (Three pictures to right) If limestone is heated in a furnace, it decomposes to produce white calcium oxide (quicklime). If water is dropped onto the calcium oxide, a vigorous reaction takes place in which heat is given off.The blocks swell and crumble, and the water is turned
to steam.The dry powder left behind is calcium hydroxide.
For more on calcium, see Volume 3: Calcium and Magnesium in the Elements set.
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