021919c

Cross laminae of mica (bright colors and shades of brown) and quartz (gray and white). Thin section photomicrograph. 2.5 mm wide field of view.

Sandstone in thin section

Poorly sorted sandstone cemented by calcite (pink).

Muscovite (mica) in sandstone.

Both from the Cretaceous Rodessa Formation in Citronelle oil field, Alabama. About 2 miles below the surface. Both photos taken using crossed polarized light.

Laminated sandstone with mica

Blatant plug

http://darknebula.storenvy.com/

So, my kid is making & selling jewelry. You might want to check it out.

Crystals, small ones

Brick-shaped dolomite crystal encrusted by a fan of silica. Long dimension 0.1 mm (1/250th of an inch).

polyq

This ... is your quartz on drugs.

psychedelia

Into the coral forest, armed with quartz and weapons-grade dolomite!