Sir: Gutzmer and Beukes (1998) have revised the sedimentary-diagenetic mode of origin suggested earlier for the todorokite-rich (with birnessite, manganite, braunite, and bixbyite) manganese deposits of the Penganga Group, India (Roy, 1981; Roy et al., 1990; Bandopadhyay, 1996), concluding that these Mn oxide deposits were entirely derived by supergene alteration of a Mn carbonate protolith which they discovered in one deep quarry section (near Nipani) below the Mn oxide ore horizon. I congratulate the authors for this discovery of the Mn carbonate horizon that eluded us in spite of thorough search (Roy et al.,...

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