monohydrocalcite
/ˌmɒnə(ʊ)ˌhʌɪdrəˈkalsʌɪt/Mineralogy
noun
A hydrated trigonal form of calcite, CaCO3·H2O, that is white to greyish or light green in colour and occurs in massive form.
Origin
1960s; earliest use found in American Mineralogist. From mono- + hydro- + calcite, after Russian monogidrokal′cit.