Browse Items (41 total)

Some alteration has produced epidote, most of the hornblende is prismatic and occurs in two colors

Contains sutured grain boundaries, conversion of hornblende to magnetite, and some fine-grained alteration products

Quartz and feldspar exhibit fracturing

Contains biotite, orthoclase, hornblende, quartz, and titaniferous magnetite

Ophitic texture in thin section, some opaques

Gabbro associated with syenite ring dike near Concord, North Carolina

Quatz appears strained, microcline is altered to muscovite and sericite, biotite is altered to chlorite

Extensively used in highway construction

Biotite forms lineation in some hand specimens, much of the quartz and feldspar is fractured

Fedlspar and quartz exhibit fracturing

Biotite and feldspar are aligned, giving the rock a texture like porphyroblastic gneiss, some feldpsar has been altered to sericite, and some larger feldspar crystals are fractured

Contains orthoclase, ligoclase, and quartz phenocrysts and has alterations of kaolinite, sericite, and epidote

Quartz and feldspar phenocrysts, rounded diabase inclusions

Plagioclase altered to epidote and flaky sericite, rock has undergone slight metamorphism

Some feldspar shows slight alteration

Phenocrysts of lath shaped feldspars and beta quartz

Quartz and feldpsar grains are closely interlocked and grains appear to be shattered

Mostly quartz, oligoclase, and microcline

Similiar in composition, texture, and shape to the Concord, North Carolina complex