particles, the three particles indicated by white arrows were identified as phytoliths.
However, identification may be rendered difficult owing to weathering or the
presence of composite particles containing different materials. In that case, SEM
image (Fig. 4.12a), element maps (Fig. 4.12b, c), and micrographs (Fig. 4.12d) are
effective tools for distinguishing among volcanic glass, phytoliths, and crystalline
minerals. An important point is that the same sample must be used for both
polarizing microscope and SEM-EDX observations. For a detailed procedure, see
footnote
1 .
Fig. 4.11 Occurrence of phytoliths. (a) Udand profile displaying abundant phytoliths in the
0.05–0.02 mm fraction of the A1 horizon, (b) present-day vegetation, (c) optical micrograph of
the 0.05–0.02 mm fraction
1 The first step is to prepare a sample for both polarizing microscope and SEM observations. To do
so, spread sample particles on a glass slide without overlapping. For the 0.05–0.02 and
0.02–0.005 mm fractions, place about 2–3 mg of air-dried powder on a glass slide by hand, and
perform the following procedure: tilt the slide, holding one side of the slide, tap the other side of the
slide on a table so that the particles gradually slide down and spread evenly on the slide.
Use one side of transparent double-sided sticky tape to pick up the particles from the glass slide,
and stick the other side of the tape to a cover glass. A disk-shaped cover glass is more convenient for
handling than square one. Put the cover glass on a glass slide, and then put the slide on the rotating
stage of a polarizing microscope (Lynn et al. 2008). Take photographs with plain and crossed
polarizers at least 2 different angles separated by 45
to distinguish isotropic (non-crystalline) and
anisotropic (crystalline) particles (Fig. 4.12d). Use the photographed particles for the next step.
4.3 Secondary Non-crystalline Inorganic Constituents
71
However, identification may be rendered difficult owing to weathering or the
presence of composite particles containing different materials. In that case, SEM
image (Fig. 4.12a), element maps (Fig. 4.12b, c), and micrographs (Fig. 4.12d) are
effective tools for distinguishing among volcanic glass, phytoliths, and crystalline
minerals. An important point is that the same sample must be used for both
polarizing microscope and SEM-EDX observations. For a detailed procedure, see
footnote
1 .
Fig. 4.11 Occurrence of phytoliths. (a) Udand profile displaying abundant phytoliths in the
0.05–0.02 mm fraction of the A1 horizon, (b) present-day vegetation, (c) optical micrograph of
the 0.05–0.02 mm fraction
1 The first step is to prepare a sample for both polarizing microscope and SEM observations. To do
so, spread sample particles on a glass slide without overlapping. For the 0.05–0.02 and
0.02–0.005 mm fractions, place about 2–3 mg of air-dried powder on a glass slide by hand, and
perform the following procedure: tilt the slide, holding one side of the slide, tap the other side of the
slide on a table so that the particles gradually slide down and spread evenly on the slide.
Use one side of transparent double-sided sticky tape to pick up the particles from the glass slide,
and stick the other side of the tape to a cover glass. A disk-shaped cover glass is more convenient for
handling than square one. Put the cover glass on a glass slide, and then put the slide on the rotating
stage of a polarizing microscope (Lynn et al. 2008). Take photographs with plain and crossed
polarizers at least 2 different angles separated by 45
to distinguish isotropic (non-crystalline) and
anisotropic (crystalline) particles (Fig. 4.12d). Use the photographed particles for the next step.
4.3 Secondary Non-crystalline Inorganic Constituents
71