Packed Sand Grains

Microscope photograph: A cluster of clear, yellow, angular crystals may be calcite or quartz growing in a cavity.

Microscope photograph: An olive-gold, granular surface suggests glauconitic or iron-stained sand.

Microscope photograph: Pale-yellow angular grains and a brassy glint sit in a dark granular matrix.

Microscope photograph: An orange-stained surface with a dark patch suggests iron-oxide cement.

Microscope photograph: A dark surface carries white streaks and a curved feature that may be a shell fragment.

Microscope photograph: A dark, fine-grained surface with white specks may be the outer skin of a black pebble.

Microscope photograph: An orange-stained surface shows brassy sparkles, likely pyrite or iron oxide.

Microscope photograph: A pitted, sandy matrix with cavities and small white grains suggests porous sediment.

Microscope photograph: A clear, glassy grain sits in an orange-stained, pale matrix.