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
That's What Girls Are Made For successful run for the group, who later found success with neighboring Detroit label Motown Records in the mid-1960s and Philadelphia soul-based records with Atlantic Records in the 1970s. That's What Girls Are Made For "That's What Girls Are Made For" is the debuting single for the American R&B/Soul vocal group The Spinners, released on Harvey Fuqua's Tri-Phi Records label in 1961. The single featured most of the original members of the group including original lead singer Bobby Smith and featured a very young Marvin Gaye playing drums. Harvey Fuqua and his then-girlfriend Gwen Gordy made the song simply for them