Blackboard ‘chalk’ are produced especially for use with blackboards in white and also in various colours. White chalk sticks are made mainly from calcium carbonate derived from mineral chalk rock or limestone, while colored or pastel chalks are made from calcium sulfate in its dihydrate form, CaSO·2HO, derived from gypsum. Chalk sticks containing calcium carbonate typically contain 40–60% of CaCO (calcite). As compared to whiteboards, blackboards still have a variety of advantages: On the other hand, chalk produces dust, the amount depending on the quality of chalk used. Some people find this uncomfortable or may be allergic to it, and according
Pick-up sticks (Haida) Pick-up sticks (Haida) Haida pick-up sticks exist in two sorts. There were non-decorated thin playing sticks (not collected) and the other decorated, containing three sets of sticks. These were named after animals or birds only known by the owner or his family, according to Charles F. Newcombe. The decoration consists of rings and spiral markings for distinction. Most elaborated sets may contain a Haida art gallery of more than fifty drawings. Made of maple wood, they are decorated with pyro-engravings or carvings. Many pyro-engravings are inlaid with copper or abalone shell. The drawings are complex and an artistic challenge as