malm

noun

1.
a soft whitish calcite
limestonestick chalk
2.
brick made with sand and slaked lime rather than with clay; usually a light gray or off-white color.
calcium-silicate brick flintlime brick sand-lime brick sandlime brick
3.
a loose and crumbling earthy deposit consisting mainly of calcite or dolomite; used as a fertilizer for soils deficient in lime
marl