| ̷ ̷ ̷ ̷ at hydro- + noun
Etymology: German hydromagnesit, from hydr- + magnesit magnesite, from French magnésite
: a mineral Mg 4 (OH) 2 (CO 3 ) 3 .3H 2 O consisting of a basic magnesium carbonate occurring in the form of small white crystals or chalky crusts