Sedimentary rocks

  • Breccia:

    • Characteristics:

    • Large grains (e.g., pebbles).

    • Angular grains.

    • Poorly sorted.

    • Environment: Terrestrial.

  • Conglomerate:

    • Characteristics:

    • Large grains (e.g., pebbles).

    • Rounded grains.

    • Poorly sorted.

    • Environment: Terrestrial.

  • Sandstone:

    • Characteristics:

    • Sand-sized grains.

    • Clastic composition.

    • Environment: Terrestrial or shallow marine.

  • Shale:

    • Characteristics:

    • Very small particles (invisible to the naked eye).

    • Composed primarily of mud and clay-sized grains.

    • Usually dark gray to black, layered, and fissile.

    • May contain organic material.

    • Environment: Terrestrial or marine.

Biochemical Rock Types

  • Coquina:

    • Characteristics:

    • Composed of shell fragments.

    • Reacts with acid (presence of Calcium Carbonate).

    • Environment: Shallow marine.

  • Fossiliferous Limestone:

    • Characteristics:

    • Contains fossils and reacts with acid (calcium carbonate).

    • Environment: Shallow marine.

  • Microcrystalline Limestone:

    • Characteristics:

    • Crystalline appearance, often gray.

    • Similar in appearance to Chert but DOES react with acid (calcium carbonate).

    • Environment: Deep marine.

  • Chalk:

    • Characteristics:

    • Soft texture, can be scratched by a fingernail.

    • Reacts with acid (calcium carbonate) and composed of dissolved shells of micro-organisms.

    • Environment: Deep marine.

Chemical Rock Types

  • Chert:

    • Composition: Microcrystalline quartz.

    • Characteristics:

    • Resembles microcrystalline limestone but does NOT react with acid.

    • Can be gray or reddish.

    • Environment: Deep marine or terrestrial.

  • Rock Salt:

    • Composition: Primarily halite.

    • Note: Often associated with evaporite environments (merchandise such as Himalayan salt lamps).

  • Rock Gypsum:

    • Characteristics:

    • Similar to mineral gypsum, sometimes has a fibrous appearance.

    • Can be scratched with a fingernail.

    • Note: Evaporite characteristics.

Organic Rock Types

  • Coal:

    • Characteristics:

    • Shiny appearance and black color.

    • Composed of decomposed plant matter and fossilized carbon.

    • Environment: Terrestrial.

    • Note: Formed via processes of compaction and lithification of organic materials over significant time periods.