It represents the pentahydrate of magnesium carbonate, and has the total formula MgCO3·5H2O .
[2] Landsfordite was discovered in 1888 in a coal mine in Lansford, Pennsylvania.
It crystallizes in the monoclinic system (space group P21/c[3]) and typically occurs as colorless to white prismatic crystals and stalactitic masses.
[4] It is a soft mineral, Mohs hardness of 2.5, with a low specific gravity of 1.7.
[5] The mineral will effloresce at room temperature, producing nesquehonite.