Breccia is a clastic sedimentary rock that is composed of large (over two millimeter diameter) angular fragments. The spaces between the large fragments can be filled with a matrix of smaller particles or a mineral cement which binds the rock together.
Colour: Variable.
Texture: Consists of angular rock fragments (2 mm to many metres in diameter) set in a fine- to medium grained matrix.
Structure: Bedding not usual, though in some types of breccia bedding is apparent in the matrix. Fossils rare.
Mineralogy: The fragments may be of any type of igneous, metamorphic or sedimentary rock. The matrix usually consists of silt or sand cemented by calcite or silica.
Field relations: Many breccias represent consolidated talus or scree material, that is accumulations of rock fragments formerly lying on steep hill slopes, or at the foot of cliffs. They are often found above uncomformities, and associated with conglomerate, arkose and sandstone. Other breccias are produced by the fragmentation of rocks during faulting.
Directly under your title (Dani Geologist!) you used the word "alot". It appears very often on emails and texts.
ReplyDeleteA check with your dictionary will show that alot does not exist. It should be written "a lot".
There is the word "allot", but its meaning is very different.