#MinCup23 Calcite vs opal. Got to be calcite: an amazing mineral, which can crystallize directly from magmas, from almost every kind of fluid, and in living plants and animals.

And amazingly useful as a geochemical and isotopic tracer of processes and time.

And best of all, an almost unparalleled complexity in crystal forms. In Goldschmidt's Atlas der Krystallformen, plates 3 to155 *just cover calcite* - this is just one of them🤩 🤯 🥰
#Geology #Mineralogy #Calcite