194 THE FLORIDA ANTHROPOLOGIST

2006 VOL. 59(3-4)

 

Table 1. Pumice artifacts from museum collections., continued.

Ft. Center GL13 dome-shaped w/ one FLMNH A16334
flat surface

Ft. Center

 
 
 
 
 

 
 

GL13 large loaf-shaped clast | FLMNH A16093

 

Ft. Center GL13 one cup-shaped
depression

  

of broken, perfectly round glass vesicles. Most specimens
examined in this study are examples of tube pumice, with
densely packed vesicles (Table 2). Figure 3 illustrates some of
the varied pumice textures observed within the study sample.

MDC.1.370.12
Miami Circle (8DA12)

rota a
1 2
in inches

Figure 2. Highly iridescent or chatoyant pumice, Miami
Circle (MDC.1.370.12).

 

GL13 one smoothed, convex FLMNH 098767
surface

opposite faces
depression
flat surface

GL13 sub-rounded, discoidal
clast

FLMNH A16262b

FLMNH A16262c
FLMNH A16262d
FLMNH A16262e

      
      

Inclusions

A Bausch & Lomb 20x Hastings loupe was used to examine
the surface of each specimen for inclusions. Several types of
inclusion were noted in the sample, including phenocrysts,
autoliths, and xenoliths. Phenocrysts are crystals visible in the
pumice groundmass. Phenocrysts typically noted in the pumice
specimens were large, milky white amphibole and clear
plagioclase crystals, and black or brown platy crystals of
biotite. Phenocrysts were very common in the assemblage
(Table 3). Other inclusions include autoliths, which are pieces
of volcanic glass that have reformed within the pumice
groundmass, and xenoliths, which are inclusions of other
volcanic rock fragments. The autoliths in the pumice analyzed
were typically melted shards of volcanic glass, surrounded by
a void and slightly white area of the pumice groundmass.
Xenoliths noted were typically black rock fragments, but
examples of gray and brown rock fragments also were noted.

Surface Cortex

In most cases the pumice artifacts considered here had
weathered exterior cortices, often a darker color than the
material exposed at fresh broken surfaces (Figure 4). The
weathered surface usually was chalky or matte in appearance
and texture. Some examples did not have weathered surfaces,
but were bright and lustrous.

Maximum Dimensions

Measurements along three axes (length, width, and height)
were made in centimeters with vernier calipers. Specimens
ranged in size considerably, from small clasts around 1.2 cm
long to large examples around 13.7 cm long (Figure 5). The