Phyllosilicate alteration minerals are commonly found in low petrologi
c types of carbonaceous chondrites. Previous spectral studies have exa
mined Mg-bearing phyllosilicates with limited success in matching the
spectral properties of CM and CI chondrites. Transmission electron mic
roscope and other analytical techniques suggest that Fe-bearing clays
are more abundant in CI and CM chondrites than magnesian varieties. He
re, we present the results of an examination of the reflectance spectr
a of Fe-phyllosilicates, including serpentines and berthierines, of wh
ich the latter were formerly known as septechlorites. We have measured
the diffuse reflectance spectra of powdered samples from 0.3 to 25 mu
m. We find that these minerals provide a better spectral match to man
y of the features seen in CI and CM chondrites, and simple linear comb
inations of the spectra of both Fe-and Mg-phyllosilicates closely appr
oximate the spectra of CM and CI chondrites.