Rounded White Grains In Dark Cement

Microscope photograph: Pale, rounded grains and small cavities sit in a glossy amber-brown cement, which may be phosphate or iron cement.

Microscope photograph: Two clear, glassy grains rest on a tan, sandy matrix, likely quartz or calcite.

Microscope photograph: Clear grains sit in a brown, sandy matrix with orange iron stain.

Microscope photograph: A pale, elongated grain lies in an olive-gold sandy matrix, which may contain glauconite.

Microscope photograph: Densely packed tan and clear grains suggest a cemented sandstone.

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.