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Lithified, round clasts having a diameter greater than 2.0mm. Chert/jasper/quarts clasts with calcite cement.
Beware, the rock contains calcite only as a cementing agent. Do not mistake it for limestone. |
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| Granola Bar Loosely compacted and lithified fossil hash. Generally comprised of angular clasts greater than 2.0mm in diameter, but it is not a breccia. Remember it is a chemical ppt because the individual clasts are chemical ppt. Beach deposit from the gulf of california. |
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| Looks like sandstone. Remember the microscope if your best friend. Microscopic examination will reveal the presence of oolites. Oolites are spherical/highly rounded sand-size grains that are made of concentric rings (spheres) of calcite. |
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| Lithified, angular clasts having a diameter greater than 2.0mm. Notice the very angular nature of the clasts. The clasts look like quartz, but they are actually fluorite (verify this with the hardness test). |
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| 100% quartz. Lithified clasts having a diamter of 1/16 to 2.0mm. Wind blown sands are usually fine grained sands nearing 1/16mm, and have frosted (not polished) surfaces. |
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Very fine grained crystalline calcite. Rock usually exhibits conchoidal fracture.
(to me, it looked like the lines of it glowed under the microscope.) |
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| Very fine grain gray to white crystalline quartz. Easy to identify the quartz because it is the only common chemical ppt (sedimentary mineral) that is hard. |
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| Unlithified clasts with a grain size between 1/16 and 2.0mm. Use a microscope to identify several minerals including quartz and calcite. Note the especially shiny, polished nature of the quartz clasts. |
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| Greater than 50% calcite. Presence of abundant fossils makes it easily identified. |
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| Looks like chalk, looks like haolinite, but reacts with HCl. Comprised of microscopic tests (Like shells) for single celled plants and animals. |
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| Lithified clasts having a diameter of 1/16-2.0mm makes it a sandstone. Look closely to observe quartz and pink orthoclase, which are the essential minerals in the identification of granite. Comes from the weathering of grantie-terrain. Note the angularity of the grains. It implies the grains have been subjected to little transportation. |
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| Note the gritty feel, but individual grains are invisible. Grains are less than 1/16mm but greater than 1/256mm. Redness due to the presence of hematite and indicates that the deposition of the silt occured in an oxidizing, probably terrestrial environment. |
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| Very fine grain red crystalline quartz. Easy to identify the quartzm because it is the only common chemical ppt that is hard. |
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| Borderline between silt and sand size clasts. Main issue is to recognize it is not a limestone. |
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| banded or layered calcite resulting from the precipitation of calcite from solution in caves. |
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| Lithified, calcareous (made of calcite)sand-sized clasts. Since the rock is 100% calcite it is a limestone.. Grains are produced by weathering, not growth like oolites are so shapes are irregular. |
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| Lithified clasts having a diameter of 1/16-2.0mm. The name is german meaning "gray stone". Abundant quartz, but always has rock fragments as grains of sand. Presence of clay matrix. To see the clay matrix, poke at the material under the microscope, notice the softness of the material between the grains of sand. |
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| Mono-mineralic rock comprised of gypsum. Test for hardness, gypsum can be scratched with your fingernail. |
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| Very fine grained, lithified clasts less than 1/256mm in diameter. Grains are invisible and smooth. Fossils help to determine the rock is clastic. |
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| Very find grain dark grey to black crystalline quartz. Easy to identify the quartz because it is the only common ppt that is hard. |
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Arkose
Clastic, <50% limestone
Clast size: 1/16-2.0mm
Lithified Sandstone with dominant grains of granite |
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Breccia
Clastic
<50% limestone
Clast Size: >2.0mm
Lithified Angular Clasts |
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Calcarenite
>50% Calcite
Type of Limestone
Lithified Calcareous Sand |
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Chalk
>50% Calcite
Soft, Microfossiliferous Limestone
usually white/earthy appearance |
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Chert
Crystalline (Chemical PPT)
Quartz is the dominant mineral
if it is not red or black it is chert. |
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Conglomerate
Clastic
<50% calcite
Clast size is >2.0mm
Lithified, rounded clasts. |
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Coquina
Granola bar
>50% Calcite / Type of limestone
Loosely compacted and cemented fossil hash
Clasts are >2.0mm. |
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Flint
Crystalline (chemical ppt)
dominant mineral is quartz
rock is black. |
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Fossilliferous Limestone
>50% Calcite
Abundance of fossils |
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Fossil Sandstone
Clastic
<50% calcite
Clast size 1/16-2.0mm
Lithified clasts with no distinct characteristics except the fossils. |
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Graywacke
clastic
<50% calcite
clast size: 1/16-2.0mm
Lithified clasts with dominant lithic grains and clay matrix. |
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Gypsum
Crystalline (chemical ppt)
Dominant Mineral: gypsum
Can scratch with fingernail |
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Jasper
Crystalline (chemical ppt)
Dominant mineral: quartz
rock is red |
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Micrite
>50% calcite / form of limestone
Cryptocrystalline calcite
conchoidal fracture
aka-lithographic limestone |
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Oolitic Limestone
>50% Calcite/form of limestone
Consisting of oolites - spherical grains of sand
concentric rings of calcium carbonate surrounding a tiny shell fragment |
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Quartz Sandstone
very gritty
<50% Calcite
Clast size is 1/16-2.0mm
Sandstone with quartz as the dominant mineral |
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Sand
Clastic
Clast size is 1/16-2.0mm
unlithified |
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Shale
clastic
clast size: <1/256mm
lithified and breaks in sheets |
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Siltstone
clastic
clast size: 1/256-1/16mm
lithified
recognize it is NOT limestone |
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Travertine
>50% Calcite/form of limestone
Banded/layered calcite
formed by inorganic ppt of calcium carbonate
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