Name: Nepheline Syenite
Type: rock
Class: Igneous
Subclass: Intermediate
Particle Size: Fine
Sample No.: Syenite_H2
Owner: JHU
Wavelength Range: All
Origin: Blue Mountain, Methuen Twp., Ontario, via Ward's Scientific (Cat.No. W-17)
Collection Date: N/A
Description: Sample from which powder was derived is a medium-grained leucocratic rock showing some foliation, consisting of plagioclase, nepheline and biotite.Particle size was 0-75 micrometers. Original ASTER Spectral Library name was jhu.becknic.rock.igneous.intermediate.fine.syenit2.spectrum.txt
Composition:

Petrographic Description:  An inequigranular rock with some foliation due to
the subparallel alignment of the long axes of feldspars and mica.  The
plagioclase is subhedral with albite and ocasionally Carlsbad twinning as
well.  The alkali feldspar anhedra can show grid-iron or Carlsbad twinning.
The nepheline anhedra often contain rounded inclusions of microcline, are
slightly turbid and frequently contain sericitic alteration along fractures.
Some of the nepheline contain abundant grains of a clear mica (muscovite) 
as an alteration product; in some cases the nepheline is almost completely
replaced by mica grains.  In addition, there are scattered subhedra of brown
biotite and less abundant anhedra of dark green (Fe-rich) biotite.  The
average modes were 45% plagioclase, 26% alkali feldspar, 3% muscovite
(including sericite) and 1.5% biotite.  No carbonate was seen in thin section,
but very weak spectral features indicate that some is present.

Microprobe Analysis:  The microprobe analysis revealed two modes of 
feldspar composition; Or94 and pure albite.  The nepheline analyses were 
consistent and indicated a composition equivalent to 17% kalsilite.

Chemical Analysis:
SiO2  59.85
CaO  0.16
TiO2  0.03
Na2O  9.69
Al2O3  22.07
K2O  5.18
Fe2O3  0.23
H2O  0.93
FeO  1.06
P2O5  0.0
MnO  0.02
MgO  0.04
TOTAL  99.26  (CO2 not analyzed)
