Andesite Tuff
Rock Sample:
The color is mainly blue and black. The sample is aphanitic and the cross section of the sample reveals very fined grained phenocrysts (~1mm in diameter). The colors of the phenocrysts range from white, blue, black, or green.
It has rough sandy feel to it. There is some major chemical weathering. There is some white residue on the surface which has a minor reaction to Hydrochloric acid.
-Hardness = 5.5
-Streak = The dark spots on the sample had a dark-brownish to yellow streak, while the blue part of the sample did not have a streak.
Thin Section:
Oxidation is shown in the thin section. The matrix has blue swells. Some of the pyroxene crystals are very fine grained and show exhibit a "swirly" texture. The plagioclase crystals exhibit some crytsal-zoning. The sample is hypocrystalline. Others are fractured and filled in with very fine grained matrix. There are large fractures within the pyrozene crystals as well. Matrix is intergrown into coarse grained quartz.
-Quartz (40%)
-Pyroxene (25%)
-K-feldspar (20%)
-Plagioclase (15%)
-Magnification at 4x/0.10
Scanning Electron Microscope:
The blue mineral that is found through out the sample is made up of silicon, oxygen, carbon, calcium, sodium, and aluminum.
1969
Western Minerals, Inc.
TMJ-18
Clay and Stilbite Matrix in Sandstone
Rock Sample:
The sample appears to be a conglomerate of crystals.The color is tan to dark green. The rock has low specific gravity . There are green, white, and brownish-orange clasts. There are some minor fractures on the outside of the sample. There is some very light banding of minerals. There is an orange coating that could be evidence of chemical weathering.
It has rough sandy texture, and is very brittle.
Thin Section:
There is a very fine matrix with semi-rounded quartz and multiple zoned crystals. The crystals are very disorganized within the thin section. Some of the plagioclase crystals show non-uniform twinning. It is similar to tartan twinning, at a 70 degree angle. Some of the pyroxene is very fine grained and are clumped together in a swirling formation.
-Quartz (40%)
-K-feldspar (20%)
-Plagioclase (20%)
-Pyroxene (15%)
-Biotite (5%)
-Magnification at 4x/0.10
1969
Western Minerals, Inc.
TMJ-17
Basaltic Tuffaceous Conglomerate
Rock Sample:
The overall matrix is a dark green blue but there are many different colored clasts that give it a mixture of colors. The color of the clasts range from brick red, pink, white, and green (non-reactant to acid). The texture of the rock is silty. There are massive, very coarse grained clasts that are up to 3cm in length. There are clasts within other clasts. There is one fracture spanning across the rock. There is evidence of minor chemical weathering. The overall shape of the rock is an octahedral. It has eight faces and forms into a jagged ball.
Thin Section:
The matrix has many globular, navy blue crystals, with an outer shell around them (XPL). Some plagioclase crystals experience tartan twinning. Also, some of the plagioclase is intergrown within other plagioclase crystals. The matrix has a variety of colors in XPL (navy blue, yellow, and brown in various shades), and makes up the majority of the thin section. There are some smaller dark blue crystals that are in the shape of a half spoked wheel (under XPL). There are some very fine grained sized glass crystals within the thin section.
-Plagioclase (50%)
-Quartz (20%)
-Pyroxene (10%)
-Olivine (10%)
-Biotite (10%)
-Magnification at 4x/0.10
1969
Western Minerals, Inc.
TMJ-16
Pumpellyite Prehnite Basaltic Tuff Breccia
Rock Sample:
The color is mainly a very dark green to dark grey. Some parts of the rock exhibit greasy luster. There are some tannish white spots and some slightly larger dark brown spots. The tannish white mineral reacts with acid. There are dark green and faded dark green phenocrysts(~3mm in size). There are medium to coarse grained white phenocrysts (2-10mm). Some phenocrysts touch each other with no matrix in between. There are some areas that possess a dark grey matrix. There are many fractures through out the sample. It has a rough and bumpy texture overall.
Thin Section:
There are many micro-fractures and veins. There are many larger fractures as well. There are also circular crystals that have a pointed center. Some of the augite crystals are severely fractured, and have quartz veins running through the fractures. There are many elongated quartz crystals that are curved. There is some glass intergrown into the circular crystals.
-Matrix (55%)
-Augite (25%)
-Quartz (10%)
-Plagioclase (10%)
-Magnification at 4x/0.10
1969
Western Minerals, Inc.
TMJ-15
Basaltic Tuff Breccia of Actinolite Greenschist
Rock Sample:
The sample is brown to white to green in color. It is porphyritic and has foliations that fan out. There are also wide fractures (≤1mm in length). There is a brownish orange coating which is evidence of chemical weathering. There are some holes around the oxidation zones which suggest deep weathering by a liquid. The sample does not react with acid. It has a silty yet jagged texture.
Thin Section:
There are micro-fractures that are non-uniform. The sample is holocrystalline. The majority of the matrix intergrows within many of the larger crystals. The rest of the thin section has a matrix that cannot be identified from a standard microscope.
-Chlorite (30%)
-Muscovite (10%)
-Serpentine (5%)
-Epidote (5%)
-Magnification at 4x/0.10
1969
Western Minerals, Inc.
TMJ-14
Dolerite Sill
Rock Sample:
The rock is dark green throughout, with a mineral forming white specks. The white mineral does not react with hydrochloric acid. The texture is very rough, and the rock's edges are sharp. Large flat phenocrysts (~ ≤10mm). The sample is non-foliated and has an aphanitic matrix. There is a off-white colored crystal forming on one of the faces. They are bumpy and <0.1mm in depth. There is some minor 70 degree cleavage on the sample.
Thin Section:
There are micro-fractures, and many of the minerals have a blue-green tint in PPL. There are also larger fractures throughout the thin section. The sample is holocrystalline with some brown glass-like blotches. There is a poikilitic texture while viewed in XPL.
-Augite (~30%)
-Plagioclase (~60%)
-Olivine (5%)
-There is little to no quartz
-Magnification at 4x/0.10
Scanning Electron Microscope:
The light green filament on the face with the label is composed of iron, calcium, silicon, aluminum, magnesium, sodium, oxygen and small amounts of carbon.
1969
Western Minerals, Inc.
TMJ-13
Greenschist
Rock Sample:
The sample color is light brown to dark brown in color with white residue through out the surface. The rock has a light green tint. There is a greasy luster to the sample. There are large white veins and planes of cleavage that follow a foliation pattern. The large white veins react with acid. There is a petal-like residue of white and brown minerals. The sample experienced chemical weathering. The rock has a silty texture.
Thin Section:
There are some small veins. The matrix is too small to identify with a microscope but it is dark in color while under PPL and a very light yellow color under XPL. Some of the plagioclase is curved. The matrix intergrown in many of the quartz crystals. The sample is holocrystalline.
-Quartz (75%)
-Unknown Matrix (~15-25%)
-Plagioclase (~7%)
-Magnification at 4x/0.10
1969
Western Minerals, Inc.
TMJ-12
Amphibolite
Rock Sample: <br />The color is a shiny dark grey with a bluish tint. Some parts of the sample are a more dark turquoise. Some faces are lighter and or darker than other faces. There is also a face with a brownish color and another face with a tannish color. The majority of the sample feels silty/sandy but there is one face that feels waxy. There are coarse grained blue-green phenocrysts, ranging in size of (2-8mm). Some of the phenocrysts are white linear phenocrysts (≤10mm in length). The matrix is apharitic. The sample experienced minor chemical weathering with some orange to brown blotches. This may have been due to oxidation. Some erosion took place on the sample, creating crater-like hole on the sides of the sample.<br /><br />Thin Section:<br />PPL. Abundant well-rounded hornblende crystals. Some of the hornblende cryststals are fairly large. The matrix has a flow-like fabric.<br />Hornblende: 50% <br />Plagioclase:30%<br />Quartz: 15%<br />Epidote:5%<br /><span>Magnification at 4x/0.10</span>
1969
Western Minerals, Inc.
TMJ-11
Granophyre
Rock Sample:
The sample color is mainly light grey to white. There is a lime green layer as well as some dark grey and brown groupings. It is pegmatic and experiences non-congruent foliation and Y-shaped fractures. There are dark brown to orange areas which indicate that chemical weathering took place. The sample has silty or sandy texture. In some spots around the sample there is a thin layer <0.1mm that resembles fine grained sandpaper in texture and color. It does not react with hydrochloric acid. Some of these "spots" are imbedded ~0.2mm in the exterior of the sample.
Thin Section:
There are micro-fractures in non-uniform formations. Also there are thick veins of quartz. The sample is hypocrystalline with fine grained size glass. Some of the pyroxene is intergrown into the quartz.
-Quartz (80%)
-Biotite (10%)
-Pyroxene (10%)
-Magnification at 4x/0.10
Scanning Electron Microscope:
The white power on the outside of the sample was made up of iron, calcium, silicon, aluminum, and little oxygen and carbon.
1969
Western Minerals, Inc.
TMJ-10
Amphibolite
Rock Sample:
The sample is very dark grey with light grey foliations.
The sample displays thin layering, some areas of chemical weathering, and microfoliations. It is aphanitic. There is quartz- like residue on the outside of the sample. It has a smooth feel throughout.
-Hardness = 5-6
-Streak = dark grey
Thin Section:
You can see very fine crystals within the thin section under the microscope. There is also a irregularly-shaped fracture within a quartz crystal. The sample is hypocrystalline, fine to medium sized glass crystals that flow with the rest of the minerals. A lot of the quartz is intergrown within augite crystals.
-Quartz (75%)
-Augite (20%)
-Plagioclase (5%)
-Magnification at 4x/0.10
1969
Western Minerals, Inc.
TMJ-09
Amphibolite, with some anthophyllite
Rock Sample:
The sample is a dark greenish blue with brown layering. On one side of the sample there is a sand-like residue that is tan in color. The sample is aphanitic and possesses micro-folds. The sample appears to have experienced some banding and rippling foliations. There is some evidence of chemical weathering which is dark brown orange in color. There is some talc or ash-like residue on some sides. It has a silty texture.
Thin Section:
The sample is hypocrystalline with very fine sized glass crystals. There is evidence of high-grade metamorphism. It has very fined grained grains especially under the microscope. The sample experiences micro-banding, micro-veins and micro-fractures.
-Quartz (70%)
-Augite (30%)
-Magnification at 4x/0.10
Scanning Electron Microscope:
The tan rough filament on the outside of the sample is made up of calcium, silicon, aluminum, oxygen, carbon. There were small signals of iron, potassium, and magnesium as well.
1969
Western Minerals, Inc.
TMJ-08
Quartz Diorite
Rock Sample:
The color of the crystals within the sample is half-white and half-black in color. The internal part of the sample feels rough, but the outside layer of the sample feels more like a fine-grained. This could be due to erosion on the exterior of the sample. There are dark and white crystals that are ≤1cm in length. There are some areas of small, light green crystal blotches. Minor chemical weathering has taken place on this sample.
Thin Section:
There is micro-twinnings within some of the plagioclase crystals. There are also some large fractures within some of the coarse-sized quartz.
-Plagioclase (45%)
-Quartz (25%)
-Clinopyroxene (30%)
-Magnification at 4x/0.10
1969
Western Minerals, Inc.
TMJ-07
Quartz Diorite
Rock Sample:
The samples color has a white matrix with dark green phenocrysts. It is phaneritic. There is evidence of chemical weathering due to the presence of a dark brownish orange film on the sample--may be oxidation. There is a sandy smooth feeling film above the TMJ-6 tag. Phenocrysts are medium to coarse grained ranging from 0.1~1cm in length. It has a rough feel overall.
Thin Section:
There is tartan twinning on some irregular-shaped plagioclase. It is a large crystal with intergrowths and many micro-tartan twinning crystal within it. Many of the irregular shaped plagioclase have many fractures or scratches in them. There is some amphibole that intergrew into some augite.
-Quartz (30%)
-Augite (25%)
-Amphibole (25%)
-Plagioclase (20%)
-Magnification at 4x/0.10
1969
Western Minerals, Inc.
TMJ-06
Quartz Diorite with Laumontite Vein
Rock Sample:
The sample color has a cream colored matrix with dark green phenocrysts. The sample contains Laumontite, which is a mineral in the zeolite group. There is a white talc-like substance on upper part of sample. Phenocrysts are medium to coarse grained ranging from 1~8mm in length. There are multiple fractures that span the length of the sample. Some of the fractures are filled in with a white talc-like powder. The sample has an overall rough texture.
Thin Section:
Small fractures are evident within the thin section. There are some blue minerals that have a birefringence of 0.004, that are biaxial (-). It somewhat swirls.
-Quartz (50-55%)
-Amphibole (25%)
-Augite (25%)
-Magnification at 4x/0.10
Scanning Electron Microscope:
The white talc like filling found in the fractures of the sample is made up of calcium, aluminum, silicon, and oxygen--this substance could be the Laumontite.
1969
Western Minerals, Inc.
TMJ-05
Quartz Diorite
Rock Sample:
The sample has black to green phenocrysts with a greenish white matrix. It has phaneritic grains with a aphanetic matrix. Phenocrysts are coarse to fined grained ranging from 0.1~1cm in size. There is a chalk like powder on the outside of the sample (white). There are deep fractures running to the center of the sample. It is likely that the sample underwent chemical weathering by oxidation. The chemical weathering is evident due to the orange brown tint. Overall the sample has a smooth weathered outside with rough gritty inside.
Thin Section:
Minerals are either medium in size. All the minerals seem to have intergrown in the quartz crystals.
-Quartz (50%)
-Plagioclase (20%)
-Biotite (15%)
-Hornblende (15%)
-Magnification at 4x/0.10
1969
Western Minerals, Inc.
TMJ-04
Hornblende Porphyrite Dike
Rock Sample:
The sample is pinkish gray with brown to green phenocrysts. There are fine-grained to medium-grained phenocrysts (0.5~5mm in length). There is a dark-brown to orange coating, which is evidence of chemical weathering due to oxidation. The matrix is white. The sample has an overall rough texture.
Thin Section:
There are grains of various sizes. There is major mixing of plagioclase and hornblende in one section where the hornblende is intergrown into the plagioclase crystals.
-Matrix is Quartz (50%)
-Hornblende (20%)
-Garnet (10%)
-Plagioclase (10%)
-Biotite ( 10%)
-Magnification at 4x/0.10
1969
Western Minerals, Inc.
TMJ-03
Hornfels, Dark Brown
Rock Sample:
The sample is fine-grained, and the majority of the rock is dark grey in color. There is a 2.5x4cm white crystal formation on the upper edge of the sample. There are fractures running through the sample. There is some chemical weathering found on the outside of the sample. The chemical weathering is rust-like in color, likely indicating an oxygen and iron reaction. The sample is densely spotted with hornfels. It has a smooth texture overall.
Thin Section:
There are some micro-fractures with clusters of plagioclase (1~5mm in diameter). There is a single euhedral garnet crystal that is enclosed in another mineral. There are some inter growths of the matrix within some of the larger plagioclase samples.
-Cordierite (50%)
-Plagioclase (40%)
-Quartz (9%)
-Other/matrix (<1%)
-Magnification at 4x/0.10
1969
Western Minerals, Inc.
TMJ-2
Hornfels, Green Diopside bearing
Rock Sample:
The sample is metamorphic. It is green to light-green in color. There are very course grained tabular zones of metamorphism (12x4cm) and light to dark layering with non-uniform shapes and patterns. The grains are aphanitic. The majority of the sample has an overall smooth texture.
Thin Section:
The thin section has small vein-like fractures filled in by larger quartz crystals.There are some fractures that are not filled in. It is Quartz-rich, though the size of the quartz crystals are small.
-Quartz (80%)
-Pyroxene (20%)
-Magnification at 4x/0.10
1969
Western Minerals, Inc.
TMJ-1
Quartz-rich Metamorphic Suite--Tanzawa Mountains, Kanto Japan Western Minerals Supplementary Information
Image is of the North Side of the Tanzawa Mountains (Wikipedia)
TMJ-suite