Proposed Template Sample for Lynn-Mattapan Rhyolites

TEMPLATE FOR SOURCE OF QUARRIED VOLCANIC SPECIMENS 
SAMPLE ID  Lynn-Mattapan-1,Lynn-Mattapn-2,Lynn-Mattapan-3 
SOURCE OF INFORMATION 
Published Reference: Hermes, O.D. and Ritchie, D. 1997, Application of petrographic 
and geochemical methods to sourcing felstic archaeological materials in 
southeastern New England.  Geoarchaeology  v.12,p.1-30 
Personal communication(Name, address, date): 
LOCATION 
MA  State  Essex  County  Marblehead  Town 
42 30'  Lattitude  70 50'  Longitude  Local geographic setting 
GEOLOGIC SETTING 
Lynn Volcanics  Geologic Unit  Geologic Member 
Ash flow(?)  Geologic Occurrence (e.g.,lava flow,ash-flow, welded tuff, dike, sill, etc.) 
Unknown 
Rhyolite  Rock Type (e.g. rhyolite, dacite, andesite, basalt,etc.) 
Uncertain 
Archaeological Name (e.g., Mt.Jasper Rhyolite, etc.) 
MACROSCOPIC DESCRIPTION 
Fresh, unaltered surface 
brownish black  Color  dark grey  (if heterogeneous) 
5YR 2/1  Munsell color code  N3  (if hererogeneous) 
Altered surface 
Color  (if heterogeneous) 
Munsell color code  (if heterogeneous) 
Fracture habit 
Conchoidal 
Subconchoidal 
Splintery 
Hackly 
Planar 
Irregular 
MACROSCOPIC DESCRIPTION  and  PETROGRAPHIC DESCRIPTION 
General  General 
Uniform  Uniform 
Inequigranular  Inequigranular 
X  Porphyritic  X  Porphyritic 
Subporphyritic  Subporphyritic 
Glomeroporphyritic  X  Glomeroporphyritic 
Banded  Banded 
Trachytic  Trachytic 
Ophitic  Ophitic 
Mottled  Mottled 
Speckled  Speckled 
Veined  Veined 
Crystallinity 
X  Holocrystalline 
Hypocrystalline 
Holohyaline 
MACROSCOPIC DESCRIPTION  PETROGRAPHIC DESCRIPTION 
Grain Size  Grain Size 
X  Phaneritic  Phaneritic 
Pegmatitic (>20 mm)  Pegmatitic (>20 mm) 
Coarse-grained (5-20 mm)  Coarse-grained(5-20mm) 
X  Medium-grained (1-5 mm)  Medium-grained(1-5 mm) 
Fine-grained (<1 mm)  Fine-grained (<1 mm) 
Phenocrysts  Phenocrysts 
Shape  Shape 
X  Euhedral  X  Euhedral 
Subhedral  X  Subhedral 
Anhedral  Anhedral 
Equant  Equant 
Tabular  X  Tabular 
Prismatic  Prismatic 
Acicular  Aciculr 
Irregular  Irregular 
X  Angular/Broken 
Mineralogy  Mineralogy 
Quartz  Quartz 
Color  Color 
Max.grain size (mm) 
Estim.abundance (vol.%) 
X  Feldspar  X  Feldspar 
plag.>K-feld.  Variety 
gray-white  Color  Carlsbad-albite  Twin type 
1.5  Max.grain size (mm) 
5%  Estim. abundance (vol.%) 
Mafic mineral  Mafic mineral 
Color  Color 
Max.grain size (mm) 
Estim.abundance (vol.%) 
Other 
Color 
Max.grain size (mm) 
Estim.abundance (vol.%) 
Matrix 
Devitification texture 
0.1  Max. grain size (mm) 
Mineralogy 
X  Quartz 
X  Feldspar 
X  Biotite 
X  Sphene 
Mafic mineral  Variety 
X  Opaque mineral 
Secondary Minerals 
X  Sericite 
Calcite 
X  Epidote 
Chlorite 
MACROSCOPIC DESCRIPTION  PETROGRAPHIC DESCRIPTION 
Structures  Structures 
Vesicular  Vesicular 
Amygdaloidal  Amygdaloidal  Vesicle filling 
Miarolitic  Miarolitic 
Perlitic  Perlitic 
Banded  Banded 
Spherulitic  X  Spherulitic  weakly developed 
Lithophsae  Lithophysae 
Eutaxitic  Eutaxitic 
Pyroclastic features  Pyroclastic features 
X  Lithic clasts  X  Lithic clasts 
Relict glass shards  X  volcanic 
Fiamme  plutonic 
Other  sedimentary 
metamorphic 
Relict glass shards 
Fiamme 
GEOCHEMISTRY 
Major Elements (wt.%) 
Analytical Method 
X  XRF  Neutron Activation 
ICP  AA  Other 
3  Number of analyses (range of concentrations given for more than single analysis) 
3.67-5.20  Na2O  0.63-0.72  CaO 
0.07-0.14  MgO  0.04-0.20  TiO2 
13.13-14.27  Al2O3  2.68-4.65  K2O 
74.34-75.73  SiO2  0.07-0.09  MnO 
0.03-0.05  P2O5  1.11-1.20  tot.Fe + Fe2O3 
Trace Elements (ppm) 
Analytical Method 
X  XRF  Neutron Activation 
ICP  AA  Other 
3  Number of analyses (range of concentrations given for more than single analysis) 
815-1255  Ba  55-60  La  115-120  Ce 
80-135  Rb  125-145  Sr  215-225  Zr 
40-45  Y  25-30  Nb  60-85  Zn 
Prepared by: 
O.Don Hermes 
Department of Geology 
University of Rhode Island 
Kingston, RI 02881 
February 17,1996