Abstract: Magnesium carbonate board is prepared by mixing a neutral magnesium carbonate suspension with a fibrous material and the like, adding active magnesium, casting the resulting mixed suspension onto a porous, permeable carrier to form a layer thereon, laminating a number of said layers if desired and pressing and then heat curing the resulting platelike body.

Abstract: A gypsum moldings as building materials having high strength is obtained by use of fibrous .alpha.-calcium sulfate hemihydrate as a raw material.There are two methods manufacturing the said gypsum moldings. One of them is the wet method and the other is the dry method.The wet method essentially consists of mixing fibrous .alpha.-calcium sulfate hemihydrate suspension with reinforcers et al., papering and dehydrating the resulting mixed suspension, with or without pressing the resulting wet mat, curing and drying the mat to obtain a gypsum moldings as building materials having high strength.The dry method is roughly divided into two methods. One of them comprises adding water to fibrous .alpha.-calcium sulfate hemihydrate and molding the resulting wet hemihydrate, and the other comprises molding fibrous .alpha.-calcium sulfate hemihydrate and adding water to the resulting moldings.