Dolerite Sill

Title

Dolerite Sill

Alternative Title

Dolerite

Identifier

TMJ-13

Description

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.

Date

1969

Contributor

Western Minerals, Inc.

Spatial Coverage

Tanzawa Mountains, Japan (Zone IV)

Temporal Coverage

N/A

Accrual Method

Purchased from Western Minerals Inc.

Unit

Dolerite Sill (Zone IV)

Number of Thin Sections

1

Geolocation