Optical Properties and Chemical Compositions of Apollo 17 Armalcolites

Armalcolite present in Apollo 17 samples 74242 and 75082 displays textures which Haggerty (1973a) used as criteria for distinguishing two distinct varieties—ortho-armalcolite and para-armalcolite. Reflectivity measurements and microprobe analyses were performed on numerous grains of both “varieties” of armalcolite present in these specimens. No major differences in optical properties and no consistent compositional variations were found in these armalcolites. Therefore, the need for distinguishing two “varieties” of armalcolite, whose only major difference appears to be their paragenesis, is unnecessary and unjustified.