Geology Lab Practicum- Sedimentary Rocks

What are the 3 types of sedimentary rocks?

1. Clastic/Detrital

2. Chemical

3. Organic

Clastic/Detrital

composed of fragments of pre-existing rocks that have been weathered, transported, deposited, and lithified via compaction and cementation

Chemical

formed through mineral precipitation, often in marine environments (not always) from minerals that were dissolved in water then solidified. They often exhibit crystalline textures

Organic

form from the accumulation and lithification of organic material, particularly plant and animal remains. Rich in carbon and can contain large amounts of decomposed or fossilized biological material. COAL!!

Well-sorted 

far from source

Poorly-sorted

close to source

Angular

close to source

Rounded

far from source

Quartz Arenite Sandstone

detrital, well-sorted, can probably scratch glass, tan 

Arkosic Sandstone

detrital, well-sorted, can probably scratch glass, reddish

Breccia

detrital, poorly-sorted with angular pebble clasts

Conglomerate

Detrital, poorly-sorted with rounded pebble clasts

Fossiliferous Limestone

reacts with acid, chemical, fossils evident

Oolitic Limestone

reacts with acid, chemical, countless little ooids

Coquina

reacts with acid, chemical, almost entirely shell fragments

Shale

detrital, well-sorted, fine-grained, friable, visible layers

Mudstone

detrital, well-sorted, very fine-grained, very friable

Coal

organic, visible layers, friable, striated, black

Chert

conchoidal fracture, chemical, smooth