212 THE FLORIDA ANTHROPOLOGIST

2006 VOL. 59(3-4)

 

4
om
% vs
in inches

Figure 2. Pumice textures: a) very fine, uniform vesicular texture (sample FBAR 72.20.534.1); b) fine vesicular texture with
abundant 1-3 mm plagioclase phenocrysts (sample HMSF 896); c) coarse, vesicular texture, with abundant mafic phenocrysts
(sample MDC 1.222.11a); d) Very coarse, vesicular texture (sample MDC 1.893.1).

Physical Characteristics
Macroscopic and SEM Studies

Wheeler (2006) has provided a detailed analysis covering
the external appearance of pumice material, including parame-
ters such as physical size, shape and coloration. The outside
surfaces of all pumice samples are stained with organic mate-
rial, producing a dark, brownish- gray color. This color is not
characteristic of a fresh surface. The interior, fresh surface of
most pumice is nearly pure white (Figure 2). Igneous rocks that
are verv light in color are said to have a “felsic” color and

composition, while dark-gray to black igneous materials are
classified as having a “mafic” color and composition. The
limited number of mafic samples available for this study were
black or variegated, dark greenish-gray and purple. Thin (<0.5-
3 mm) weathering/hydration rims are present on the surface of
all samples, but the interiors of the pumice clasts appear very
fresh and are indistinguishable from modern samples.

The size of gas cavities or vesicles varies between samples;
two distinct textural types appear to be present. Most of the
samples that were studied have very smooth surfaces composed
of very small vesicles plus a few larger vesicles (Figure 2a).
The remaining samples have a coarse, sponge-like, irregular