idiochromatic
adjective
id·io·chromatic
¦idē(ˌ)ō+
: colored inherently and characteristically : having a distinctive and constant coloration
copper sulfate is an idiochromatic substance
—used especially of minerals compare allochromatic sense 1 
Word History
Etymology
International Scientific Vocabulary idio- + chromatic
First Known Use
1849, in the meaning defined above