Red shale
Red shale from the Indian River member of the Normanskill formation. This rock contains hematite, chlorite, muscovite, plagioclase, and quartz.
The thin section shows muscovite and biotite with some larger quartz grains visible and minor hematite staining.
This rock is from the chlorite zone of the Barrovian metamorphic sequence (low metamorphism).
This rock was collected from the east end of a large road cut which samples 2 and 3 were also collected from.
Western Minerals
DUCO-1
Green shale
Green shale of the Indian River member of the Normanskill formation. This shale contains muscovite, chlorite, plagioclase, and quartz.
The thin section shows quartz and biotite with some minor opaques.
This rock is from the chlorite zone of the Barrovian metamorphic sequence (low metamorphism).
This rock was collected from the east end of a large road cut where samples 1 and 3 were also collected from.
Western Minerals
DUCO-2
Graywacke
The graywacke facies in the Mt. Merino member (where sample 4 also comes from). Graywacke is a hard, dark-colored sandstone. This sandstone represents a similar rock to the protolith for the quartzite of sample 10.
The thin section shows quartz, feldspar, and lithics.
This rock is from the chlorite zone of the Barrovian metamorphic sequence (low metamorphism).
This rock was collected from the west end of a large road cut where samples 1 and 2 were also collected from.
Western Minerals
DUCO-3
Slate
Kink fold in a slate from the Mt. Merino Member.
This rock is from the chlorite zone of the Barrovian metamorphic sequence (low metamorphism).
Western Minerals
DUCO-4
Graphitic slate
A highly graphitic slate in the Walloomsac slates. Contains pyrite. This rock also contains biotite, chlorite, muscovite, quartz, ilmenite, and pyrite.
The thin section shows large biotite grains, and chlorite muscovite, and quartz. Fluid inclusions are pervasive.
This rock is from the biotite zone of the Barrovian sequence (low-intermediate metamorphism).
Western Minerals
DUCO-5
Garnet biotite schist
Schist with sparse garnet. This schist is darker and graphitic. It also contains biotite, chlorite, muscovite, feldspar, and quartz.
The thin section shows several large biotite grains with an included garnet, small quartz grains, muscovite, and many fluid inclusions.
This rock is from the garnet zone in the Barrovian metamorphic sequence (intermediate metamorphism).
Western Minerals
DUCO-6
Chloritoid schist
Schist with coarse chloritoid crystals (up to 1/8 inch) without preferred orientation. These crystals grow across the foliation developed in the schist, but appear deformed. Chloritoid is a silicate mineral made in metamorphism. It also contains garnet, muscovite, chlorite, feldspar, and quartz.
The thin section shows a large chloritoid grain, and euhedral garnet. Fine-grained muscovite and biotite are present, along with strings of an opaque, likely graphite.
This rock is from the garnet zone in the Barrovian metamorphic sequence (intermediate metamorphism).
Western Minerals
DUCO-7
Staurolite chloritoid schist
Schist bearing both staurolite and chloritoid. This marks the first appearance of staurolite in the metamorphic sequence. Also contains garnet, muscovite, chlorite, biotite, feldspar, and quartz. The assemblage in not in equilibrium.
The thin section shows large chloritoid grains with staurolite (an assemblage not in equilibrium). Fine grained muscovite and biotite are also present, along with micro-crystalline quartz and several graphite strings.
This rock is right at the transition between the garnet-staurolite zones in the Barrovian metamorphic sequence (intermediate (increasing) metamorphism).
Western Minerals
DUCO-8
Staurolite schist
Schist with coarse staurolite grains. This outcropping is approximately on the strike of the chloritoid schists (sample 7). Also contains garnet, muscovite, feldspar, and quartz. Presumed to be from the Everett Schist.
The thin section shows staurolite, biotite, muscovite (noticeable by pleochroism differences) and quartz.
This rock is from the staurolite zone in the Barrovian metamorphic sequence (higher intermediate metamorphism).
Western Minerals
DUCO-9
Quartzite
Metamorphised sandstone with a gray, glassy appearance. From the Paughquag quartzite, a late Cambrian formation. The basal Cambrian quartzite rests on pre-Cambrian gneisses.
The thin section shows quartz and plag with some biotite and grain boundaries. Many fluid inclusions noticeable.
This rock has a different protolith than the many pelitic schists around it.
Western Minerals
DUCO-10
Kyanite biotite garnet schist
Schist with coarse biotite controlling foliation. Garnets visible in some hand samples. Kyanite blades without preferred orientation--at higher concentration within folds. Possibly from the Walloomsac schist.
The PPL thin section shows biotite, muscovite, kyanite, and staurolite.
This rock is from the kyanite zone of the Barrovian metamorphic sequence (high metamorphism).
Western Minerals
DUCO-11
Muscovite schist
Extremely coarse-grained muscovite schist. Large garnets visible in hand sample. Sillimanite is not recognizable in hand sample, however.
The thin section shows muscovite (with minor sillimanite) in a large band, biotite, staurolite, and quartz.
This rock is from the sillimanite zone of the Barrovian metamorphic sequence (highest metamorphism).
Western Minerals
DUCO-12
Marble
Metamorphised Briarcliff dolostone.
The thin section shows well-twinned dolomite grains with diopside at the bottom.
Western Minerals
DUCO-13
Marble
Metamorphised Briarcliff dolostone with visible micas. Contains diopside, tremollite, and phlogopite. At the metamorphic grade of the first sillimanite isograd.
Thin section shows irregular dolomite grains in the center, with pleochroic phlogopite at top and tremolite at bottom.
Western Minerals
DUCO-14
Marble
Metamorphised Balmville limestone with visible phlogopite crystals. Also contains actinolite.
Thin section shows calcite with interspersed pleochroic phlogopite.
Western Minerals
DUCO-15
Marble
Metamorphised Balmville limestone with visible phlogopite crystals. Also contains tremolite visible at the outcrop level. Within nose of anticline of Walloomsac schist.
The PPL thin section shows a large irregular calcite grain with tremolite at the bottom.
Western Minerals
DUCO-16
Barrovian Metamorphic Sequence--Dutchess County, NY Western Minerals Supplementary Information
OCR PDF of supplemental information for the Barrovian Metamorphic Sequence--Dutchess County, NY
Western Minerals, Inc.
1980
PDF
DUCO 1-16