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Occasionally some individual crystals (phenocrysts) are larger than the groundmass, in which case the texture is known as porphyritic. A granitic rock with a porphyritic texture is known as a granite porphyry. Granitoid is a general, descriptive field term for lighter-colored, coarse-grained igneous rocks.
The Winking Man Rock formation (also known as the Winking Eye [5]) is part of the Ramshaw Rocks section of The Roaches. It looks like a face sticking out of the hillside, and as you travel past in a car towards Buxton the 'eye' appears to wink, as a pinnacle of rock passes behind the face as a consequence of parallax. [6] [5] A public house ...
The following is a list of rock types recognized by geologists.There is no agreed number of specific types of rock. Any unique combination of chemical composition, mineralogy, grain size, texture, or other distinguishing characteristics can describe a rock type.
A rock formation is an isolated, scenic, or spectacular surface rock outcrop. Rock formations are usually the result of weathering and erosion sculpting the existing rock. The term rock formation can also refer to specific sedimentary strata or other rock unit in stratigraphic and petrologic studies.
Primary rocks (geol.) a term early used for rocks supposed to have been first formed, being crystalline and containing no organic remains, as granite, gneiss, etc.; – called also primitive rocks. The terms Secondary, Tertiary, and Quaternary rocks have also been used in like manner, but of these the last two only are now in use.
Some Archean rock formations show macroscopic similarity to modern microbial structures, leading to the inference that these structures represent evidence of ancient life, namely stromatolites. However, others regard these patterns as being the result of natural material deposition or some other abiogenic mechanism.
It is an igneous rock. [6] Produced from felsic lava, obsidian is rich in the lighter elements such as silicon, oxygen, aluminium, sodium, and potassium. It is commonly found within the margins of rhyolitic lava flows known as obsidian flows. These flows have a high content of silica, giving them a high viscosity.
Shungite has two main modes of occurrence, disseminated within the host rock and as apparently mobilised material. Migrated shungite , which is bright (lustrous) shungite, has been interpreted to represent migrated hydrocarbons and is found as either layer shungite , layers or lenses near conformable with the host rock layering, or vein ...