What is Hypidiomorphic texture?
Hypidiomorphic refers to a texture, in which the grains of some mineral species are anhedral, those of. others subhedral, and those of some may even be anhedral. The texture is typical of granitic rocks in. many of which quartz and orthoclase tend to be anhedral, and plagioclase and biotite are subhedral to. euhedral. …
What is Allotriomorphic?
Definition of allotriomorphic : marked by a form different from the normal or expected because of development in special circumstances —used especially of mineral grains of igneous rocks whose mutual growths have prevented the assumption of outward crystal form —contrasted with idiomorphic.
What does Holocrystalline mean?
Definition of holocrystalline : completely crystalline : made up wholly of crystals or crystalline particles —used of a rock (as granite)
What is Idiomorphic?
Definition of idiomorphic : having the proper form or shape —used of minerals whose crystalline growth has not been interfered with.
How Hypocrystalline is formed?
Hypocrystalline (or Hyalocrystalline). Rock composed of both crystals and glass. Indicates a period of relatively slow cooling (sufficiently slow to allow crystallization) followed by quenching of the remaining magma.
What does Holohyaline mean?
Said of an igneous rock that is composed entirely of glass.
How is Holocrystalline formed?
If the cooling period is long enough to let the atoms form orderly patterns and mineral crystals fully grow, the rock then has minerals with large particle size and crystal shape, which can be seen by eyes or low-magnification microscope. In this case, the rock is known as “holocrystalline”.
What is meant by aphanitic?
Aphanitic is a descriptive term for small crystals, and phaneritic for larger ones. Very coarse crystals (those larger than 3 centimetres, or 1.2 inches) are termed pegmatitic. In igneous rock.
What do you mean by nettle plant?
/ˈnet̬. əl/ a wild plant with heart-shaped leaves that are covered in hairs that sting (= cause a painful reaction when touched): stinging nettles.
Is basalt a Hypocrystalline?
Basalts are porphyritic, with calcic plagioclase (An72–92Ab7–27Or0–1), ferroan enstatite (En59–68Fs29–37Wo3–4) and augite (En38–39Fs18–20Wo41–44) phenocrysts, in a hypocrystalline groundmass made up of bytownite (An71–85Ab14–28Or1), augite (En37–38Fs19Wo43–44), ferroan enstatite (En62–68Fs30–35Wo1–4) and rare pigeonite …
Is Obsidian a Holohyaline?
Obsidian is a holohyaline rock.
Is quartz an Aphanitic?
Aphanites are commonly porphyritic, having large crystals embedded in the fine groundmass, or matrix. The larger inclusions are called phenocrysts. They consist essentially of very small crystals of minerals such as plagioclase feldspar, with hornblende or augite, and may contain also biotite, quartz, and orthoclase.
Is Basalt a holocrystalline?
Mineralogy: The basalt samples, in hand specimen, is melanocratic, holocrystalline, medium-grained and porphyritic. Vesicles have an elongated and oval shape. Moreover, the main mineral constituents are olivine, plagioclase, pyroxene and opaque minerals (mainly magnetite).
What are phenocrysts in geology?
A phenocryst is a large crystal in an igneous rock. It is a cognate crystal, almost invariably early formed, and is genetically distinct from a xenocryst (Iddings, 1889). Its derivation is from Greek phaneros, conspicuous, and kristallos, a crystal.