Browse Items (41 total)

Contains secondary products of alteration including serpentine, talc, chlorite, carbonates, and iron oxides

Mined and marketed under the name "Aplite"

Sample comes from flow rocks that are associated with lithic fragment tuffs, pyroxene and chlorite are present as an interstitial material

Rock has been subjected to alteration and shear forces, the garnet present is probably an alteration product

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

Rock appears to be hydrothermally altered, sample is taken from a sill and is source of basaltic tuffs in area

Amphibole, epidote, chlorite, quartz, calcite, and clinozosite present are thought to be alteration products

Rock may have undergone some alteration

Fedlspar is cream-pink colored and much has been altered to sericite/epidote

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

Much of the plagioclase has been altered to epidote and sericite, hornblende occurs as long prismatic crystals arranged in sprays

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

Quarred for monumental stone, ophitic texture in thin section, minor amount of opaques

Ophitic texture in thin section, some opaques

Ophitic texture in thin section, some opaques

Ophitic texture in thin section, plagioclase exhibits some alteration to sericite

Shows considerable fracturing, thin section examination shows ophitic texture

Mostly plagioclase and biotite

Gabbro associated with syenite ring dike near Concord, North Carolina

Mostly quartz, oligoclase, and microcline