Experimental conversion of biotite to hydrobiotite
The minerals sensitive to HCl are iron calcite, iron dolomite, hematite, pyrite, magnesium iron ore, glauconite, hydrobiotite
The gangue minerals identified comprised of mainly calcite, quartz, epidote, magnetite, muscovite, hydrobiotite
, sapphirine and graphite.
In the case of all samples two main phases of hydrobiotite (peaks of high intensity at 1.
Traces of iron oxides are not-detectable in spent catalyst S4c(r), but characteristic peaks of hematite, traces of hydrobiotite and another phase, most probably muscovite, were observed for S5c(r) (Marcos et al.
Two main phases were identified: hydrobiotite
(peaks of high intensity at 1.
mica) and tosudite (Ch-Sm); trioctahedral are: aliettite (Ta-Sa), corrensite (Ch-Sm which is low charge, and Ch-Ve which is medium charge), dozyite (Sp-Ch), hydrobiotite
(Bi-Ve), kulkeite (Ta-Ch), and Bi-Ch which is not yet named.
Petrographic observations indicate that growth of vermiculite observed in the ultramafic samples occurred after the formation of biotite through an intermediate stage of hydrobiotite, in agreement with studies of vermiculite deposits elsewhere (Prasad and Majumdar, 1966; Nettleton et al.
5b represents the XRD pattern of hydrobiotite (a specific mineral name for mixed-layer structure with regularly alternating biotite and vermiculite components).
1993) described similar weathering of biotite and its t ransformation into vermiculite from volcaniclastites in central Italy, including the presence of hydrobiotite interstratified phase with a strong tendency towards regularity.
The main difference between hydrobiotite and phlogopite (Table 1) from chemical point of view is in the amount of potassium and water.
1963, Interpretation of the composition of vermiculites and hydrobiotites