biotite

Its name comes from the many biotite crystals that glitter in the sun.

Those from the more recent period, between 12,000 and 13,000 years ago, had large amounts of biotite.

Hornblende and biotite occur also, but are less common.

This interpretation is supported by the presence of shocked quartz and biotite.

It is composed mainly of quartz with feldspar and biotite.

The biotite is typically in clots or short streaks.

When biotite is found in large chunks, they are called "books" because it resembles a book with pages of many sheets.

Biotite occurs in some of these rocks, and melanite also is present.

It may contain minor amounts of hornblende, biotite and other minerals.

Biotite is the most prevalent Paleozoic metamorphic rock in the region.

Biotite is found in a wide variety of igneous and metamorphic rocks.

Small flecks of a dark, opaque mineral have been tentatively identified as biotite.

Biotite is virtually absent, but zircon is very common.

It is described as a light-gray to pale orange-pink biotite granite.

The dam sat on a foundation of silt and stable biotite gneiss (rock).

Common examples of micas are muscovite, and the biotite series.

Phlogopite is an important and relatively common end-member composition of biotite.

For physical and optical identification, it shares most of the characteristic properties of biotite.

If the rock is granite consisting of biotite (sp.

Oligoclase and biotite schist have also been pushed to the surface of the Earth.

Under cross-polarized light biotite can generally be identified by the gnarled bird's eye extinction.

For example, the common rock, granite, is a combination of the quartz, feldspar and biotite minerals.

Layering underlined by the accumulation of hornblende and biotite.

The biotite has aligned itself parallel to sigmoidal shear bands.

It is foliated and white to cream with biotite and feldspar in large crystals.