KisH

GEOCHEMICAL STUDIES OF PUMICE 211
ra rts neers te renrenrinunnerensnurnehtnreepunsatstetnperrerennnttetneerreresnensnn

Table 1. Physical Characteristics of Florida Pumice Artifacts.

Sample

Location

Site

Magnetic

Munsell Vesiculation* Alteration

Number Density! Properties” Color’
SC Vent __Propertics” __Color

Southern Florida

MDC 1.567.6b Miami Circle 8DAi2 <1.0
MDC 1.166.4 Miami Circle 8DAI2 <1.0
MDC 1.222.11a Miami Circle 8DA12 <1.0
MDC 1,472.4 Miami Circle 8DA12 <1.0
MDC 1.893.1 Miami Circle 8DA12 <1.0
HMSF 896 Brickell Point 8DA98 <1.0
FBAR 75.62.10.1 Higgs Site 8IR24 <1.0
FBAR 72.20.534 IndianKey 8MOI5 <1.0
FLMN A16262a Fort Center 8GL13  <1.0
FLMN 98576 Bear Lake 1 8M033 <1.0
HMSF 582.1 Brickell Point 8DA98 >1.0
HMSF 1018.18 Granada 8DAI1 <1.0
HMSF 2942.1 Honey Hill 8DA411  <1.0
HMSF 427.5 Custom House 8DA106 = 1.0
FBAR 74.2.10.8 Stock Island 8M02 <1.0
FBAR 00.14.47.1 Deering Estate 8DAG651 <1.0
FBAR 76.209.1.1 Shark Butchery 8SL37 <I1.0
FBAR 99.65.7.1 Whitebelt 1 8PB220 <1.0
HMSF 1874,1b Sutton Site 8DA103 <1.0
Northwestern Florida
EGLIN 056 Wynnhaven 80K239 <1.0
EGLIN 198 Wynnhaven 80K239 <1.0

M NO ME <lmm
VW 10YR 8/1 VFE <Imm
M 10YR 9/2 ME <imm
M 10YR 9/2 VCE <imm
M NO VET <Imm
M 10YR 9/2 VET 3mm
Vw 10YR 9/2 ME Imm
M 10YR 9/1 VFT <lImm
Vw NO FT <lmm
M 10YR 3/1 ME 3mm
M 10YR 5/1 CT <lmm
M NO FT <imm
M 10YR 9/1 FT 1-2mm
Ss 10YR 2/1 S <Imm
VW 10YR 8/1 VFT = _1-3mm
M 10YR 7/3 MT >15mm
WwW 10YR 8/1 FT <lmm
M 10YR 8/4 MT >15mm
s 10YR 6/4 MT 5-10mm
WwW SYR 4/1 CT <lmm
M 7.5 YR 6/1 ME <Imm
M

EGLIN 742 Wynnhaven 80K239_<1.0 10YR 7/3 FT 5-10mm

1. Density reported relative to water (1.0 gm/cm’).

2. Relative magnetic susceptibility as measured by the attraction of a rare earth magnet to individual specimens. Strong (S)— attraction
takes place at > Smm; Moderate (M) — attraction takes place at 3-5 mm: Weak (W } attraction takes place at less than 3 mm; Very weak

(VW) — magnet must touch sample to be attracted.

3. Munsell Color — color of fresh surface as viewed under indoor fluorescence lighting.

4, Vesicle size — (VC) very coarse 3-5 mm; (C) coarse 2-3 mm: (F) fine - 0.5-Imm; (VF) very fine (<0.5 mm).
(S) Scoria — coarsely vesicular basaltic rock. E - equidimensional, T - tubular.

element analyses is estimated to be approximately 1-3 percent.
The water content of the samples was estimated by measuring
the weight loss of a sample when heated to approximately
950°C for 90 minutes. This value is reported as “loss on
ignition” (LOI) in Table 4. Trace element analyses were
performed using a Perkin-Elmer Elan 600 ICP mass spectrome-
ter using standardized laboratory solutions. Estimates of the
accuracy and precision for trace element analyses range
between 5-10 percent depending upon the absolute concentra-
tion of the trace element in each sample.

The index ofrefraction for pumice glass was measured as a
means of estimating the SiO, concentration in the glass compo-
nent of each sample. Very fine, pulverized pumice (185-210
tm) was mounted on a microscope slide and immersed in
liquids with known refractive indices (Cargille Certified
Refractive Index Liquids, Series A). Measurements were made

using plane polarized light at a wavelength of 589 nm. All
measurements were made at 23°C. The index of refraction for
the pumice glass was first roughly matched to index liquids
using the “relief” of the sample versus the index liquid and then
more precisely matched using the Becke line method. The
refractive index of each sample was matched to the nearest
0.001 based on the available range of the refraction liquids.

Samples that contained visible phenocrysts, as well as a
limited number of purely vitric (glassy) samples also were
characterized by petrographic thin section analysis. The
volume percentage of different components in the thin section
sample (“mode”) was measure by standard point counting
procedures. Approximately 200 points were counted for each
sample. Modal analysis provided quantitative values for the
percent void space, glass, and mineral percentage of the
analyzed samples.