Leopardite is a widely recognized rock
name that was introduced into the geological literature in
the mid 1800s. Various descriptions of this rock in the
literature can be summarized as follows: off-white,
fine-grained aplite (or alaskite), with sporadic quartz
phenocrysts, that is characterized by dark gray to black or
brownish, roughly rod-shaped zones pigmented by hydroxides
of manganese (plus or minus iron).