『Abstract
This paper describes the ways in which the major rock-forming
primary minerals (olivine, pyroxenes, amphiboles, feldspar, micas
and chlorites) break down during weathering, the products that
develop during this breakdown and the rates at which this breakdown
occurs. The perspective chosen to illustrate this vast topic is
that of the residual soil weathering profile. Different physical
and chemical conditions characterize the various parts of such
a profile. Thus, in the slightly weathered rock at the base of
the profile, mineral weathering will take place in microfissures
and narrow solution channels and the capillary water in such spatially
restricted volumes may be expected to be close to equilibrium
with the primary mineral. In these circumstances, the weathering
product formed may be closely related to the primary mineral both
compositionally and structurally. The saprolite higher up in the
weathering profile may or may not retain the fabric and structure
of the original parent rock, but in either case the close relationship
observed between primary mineral and weathering product in the
slightly weathered rock may be lost. This part of the profile
will usually be affected by freely flowing drainage waters, the
composition of which will be far from equilibrium with specific
primary minerals. Weathering products which do form are likely
to reflect the interaction between bulk water and bulk parent
material. In the soil profile, the situation will be further complicated
by organic ligands derived from decomposing organic matter or
from the direct activities of soil microbes or plant roots. Thus,
biological weathering will assume a much greater significance
in this part of the profile compared with the mainly inorganic
processes dominating in the saprolite and the slightly weathered
rock. The general nature of any particular weathering profile
will reflect the interactions between climate, topography, parent
material, soil biota and time and superimposed upon this complexity,
when considering how individual primary minerals break down in
detail, will be factors related to the nature of the mineral itself.
Particularly important in this respect is the inherent susceptibility
of the mineral to weathering, which is related to overall chemical
composition and structure, as well as the distribution and density
of defects, dislocations and exsolution features, which often
control the progress of the weathering reaction.
Keywords: weathering; olivine; pyroxene; amphibole; feldspar;
biotite; muscovite; chlorite; soil; saprolite.』
（Introduction）
The weathering profile
Role of the primary mineral in initiating weathering reactions
Weathering of olivine
Transformations in fresh and weathered rock
Weathering in basal saprolite
Weathering in soils and upper saprolites
Weathering of pyroxenes and amphiboles
Transformations in weathered rock
Weathering in saprolite
Weathering in the upper saprolite and soil
Weathering of feldspars
Transformations in weathered rock
Weathering in saprolite and soils
Dissolution mechanism
Influence of dislocations and microtexture on feldspar dissolution
Weathering rates of feldspar and surface area
Weathering products of feldspar in saprolites and soils
Role of organic acids in feldspar weathering
Biological weathering of feldspars
Weathering of micas
Vermiculitization of mica
Kaolinization of micas
Multi-component weathering products of biotite
Weathering of micas in the soil
Biological weathering of micas
Rates of weathering of micas
Weathering of chlorites
Transformations in weathered rock
Weathering in saprolite
Weathering in soils
Conclusions
References