What is cumulative texture?
Cumulate rocks are igneous rocks formed by the accumulation of crystals from a magma either by settling or floating. Cumulate rocks are named according to their texture; cumulate texture is diagnostic of the conditions of formation of this group of igneous rocks.
What is intergranular texture?
Intergranular is a textural term indicating that a crystal occupies the angular space between at least two larger crystals. Intergranular crystals have crystallised later than the crystals that control their shape.
What is Orthocumulate?
[‚ȯr·thə′kyü·myə·lət] (petrology) A cumulate composed chiefly of one or more cumulus minerals plus the crystallization products of the intercumulus liquid.
What is interstitial texture?
Ophitic texture, a variant the poikilitic texture, is one where random plagioclase laths are enclosed by pyroxene or olivine. If plagioclase is larger and encloses the ferromagnesian minerals, then the texture is subophitic and the laths typically impinge on one another to form sharp angles.
What is Trachytic texture?
Trachytic is a texture of extrusive rocks in which the groundmass contains little volcanic glass and consists predominantly of minute tabular crystals, namely, sanidine microlites. The microlites are parallel, forming flow lines along the directions of lava flow and around inclusions.
What are the 5 textures of igneous rocks?
Igneous Rock Textures Igneous textures are used by geologists in determining the mode of origin of igneous rocks and are used in rock classification. There are six main types of textures; phaneritic, aphanitic, porphyritic, glassy, pyroclastic and pegmatitic.
How is Poikilitic texture formed?
Poikilitic texture describes the occurrence of one mineral that is irregularly scattered as diversely oriented crystals within much larger host crystals of another mineral.
What is Ophitic texture in geology?
Ophitic texture is the association of lath-shaped euhedral crystals of plagioclase, grouped radially or in an irregular mesh, with surrounding or interstitial large anhedral crystals of pyroxene; it is characteristic of the common rock type known as diabase.
What is the texture of hornblende?
Hornblende is a complex inosilicate series of minerals (ferrohornblende – magnesiohornblende)….
| Hornblende | |
|---|---|
| Color | Black to dark green or brown |
| Crystal habit | Hexagonal/granular |
| Cleavage | Imperfect at 56° and 124° |
| Fracture | Uneven |
What is Glomeroporphyritic texture?
Glomeroporphyritic or glomerophyric is a term used to describe a porpyritic texture in which phenocrysts are clustered into aggregates called glomerocrysts or crystal clots. Glomeroporphyritic textures are common and often included plagioclase and pyroxenes in basic rocks.