This mineral (*) effervesces slowly or not at all in an acid test, distinguishing it from a similar mineral.
In experiments aimed at replicating natural formation of this mineral, it precipitates within a mucus matrix secreted by sulfate-respiring bacteria to form biofilms. The puzzle surrounding this mineral is that its known contemporary natural origins are confined to a few bacterial mats under super-saline lakes and lagoons and are thus insufficient to explain its prevalence in the geological record, which may be due to anoxic conditions in ancient oceans. This mineral (*) effervesces slowly or not at all in an acid test, distinguishing it from a similar mineral. This mineral, which differs slightly from aragonite, is one of several sedimentary precursors to marble, and its namesake's first identification of it occurred in a Northern Italian mountain range now named for it, a section of the Alps. For 10 points, name this mineral, which is essentially calcite with some calcium swapped out for magnesium.
In experiments aimed at replicating natural formation of this mineral, it precipitates within a mucus matrix secreted by sulfate-respiring bacteria to form biofilms.
dolomite