pseudomorph

/ˈsudəˌmɔrf/

Other forms: pseudomorphs

A pseudomorph is kind of like a geological "imposter." It occurs when one mineral replaces another, taking on the outward shape and crystal form of the original mineral while being composed of a completely different substance.

The word pseudomorph literally means "false form." In geology, a pseudomorph occurs when one mineral replaces another but keeps the original's shape. This process also happens with organic objects: Petrified wood, for example, is a pseudomorph. Over millions of years, silica replaces a dead tree's wood cells, resulting in something that looks like a tree — complete with bark textures — but is actually solid quartz. Outside of geology, the term can describe anything that maintains an old "shell" or appearance while its internal reality has completely changed.

Definitions of pseudomorph

1. noun

   something, particularly a mineral, that looks like one thing but is actually something else
2. noun

   something that has been substantially changed from its original form but still looks like its original form
3. noun

   an unusual, misleading form