In mineralogy, a pseudomorph's a mineral or mineral compound that appears in an untypical form (crystal system), resulting from a substitution process in which the appearance and dimensions remain constant, but the original mineral's replaced by another. The name literally means "false form". Terminology for pseudomorphs's "replacer after original", as in brookite after rutile. Substitution pseudomorph An infiltration pseudomorph, or substitution pseudomorph's a pseudomorph in which one mineral… (More on Pseudomorph)