Brownspar - Term sometimes given to describe all the minerals of the calcite group as an individual mineral with different varieties. Since the minerals in the calcite group are isomorphous and exchange elements they contain with other members of the group, forming multiple solid solution series within the group, a number of scientists have classified them as one mineral, Brownspar, with different varieties, being:

All members of the group intermingle with one or two more, thus intermediary minerals exist, such as Cobaltocalcite (Ca,Co)CO₃, Breunnerite (Mg,Fe)CO₃, Oligonite (Fe,Mn)CO₃, and Sideroplesite (Fe,Mg)CO₃. Many scientists do not accept Brownspar as an individual mineral but only label these minerals as the "calcite group of carbonates". This is so because first of all, there are too many names and possible configurations, so each mineral needs individual specification, and second because the group does not form a continuous series, for many combinations of elements of minerals in this group cannot possible exist.
See also Calcite Group