How is rhyolite made


Author: Torsten Purle ( | Last update: 04/30/2021

Rhyolite - properties, formation and use

english: rhyolite | French: rhyolite

Rhyolite is named for the structure of the rock. Rhyolite is derived from the Greek with flowing stone translated - based on that Flow or fluid structure of rhyolite, or as the German geographer Ferdinand von Richthofen (1833 to 1905) wrote in 1859: "The name rhyolite is intended to indicate the occurrence in flowing masses and lava flows and for the silicic acid-rich mixtures of the new igneous rocks".
The term rhyolite was used earlier in the geological literature, for example by Heinrich Wilhelm Dove (1803 to 1879, German physicist), who named the rock in a list of rocks in 1847. Richthofen later specified the term rhyolite in the context of the distinction between rocks in "rhyolite group, trachyte group and basalt group", which he examined more closely in Transylvania / Hungary.

Properties of rhyolite

definition: Rhyolite is an igneous rock of extrusive origin, which is characterized by a porphyry structure.

The color of rhyolites is described as light to medium, varying from light brown to light gray, green and reddish, sometimes also purple going.

The reason for the color is the minerals involved in the structure of the rock.
As Main quarrel Microcrystalline quartz, volcanic glasses and alkali feldspars dominate in rhyolite; Due to the predominance of quartz, rhyolite is therefore also referred to as quartz porphyry in the literature.
The Side effects (= up to 5% involved in the composition of the rock) are biotite and hornblende, apatite and magnetite, which, as speckles in the fine-grain rock matrix, cause a porphyry structure and make the determination easier because of the abnormality. This means that the grain size of the rock is mainly fine-grained, but is interspersed with clearly visible larger crystals - a structure that is called porphyry in geology; The structure of rhyolite is visually reminiscent of concrete

The density of rhyolite is 2.5 to 2.8 g / cm3.

Formation and distribution of rhyolite

Rhyolites are counted among the igneous rocks that are formed above the surface of the earth, so-called volcanic rocks.

The formation of rhyolite takes place in two steps: First, the formation of the first larger, rock-forming crystals takes place in the volcano as a result of the cooling of the rock melt during transport towards the earth's surface. During the subsequent eruption, the rock mass continues to cool down rapidly, further minerals crystallize out - in particular so-called glasses (= amorphous, crystal-free rocks). Volcanic glasses are a testament to the particularly rapid cooling of molten rock: so quickly that - as is typical for glasses - no crystals can develop. In addition, cavities in the rhyolite indicate the nature of the lava, which in the case of rhyolite was gas-rich and viscous

The banded version is known as a variety of rhyolite. Banded rhyolite is characterized by interwoven layers that arise as a result of different structures and colors of volcanic material. Feldspars and quartz needles also appear.

Significant rhyolite deposits are located in places that are or were shaped by volcanism, e.g. Iceland, Königsstuhl, Thuringian Forest, Harz, Ore Mountains, Odenwald / Germany; Bolzano / Italy; Rocky Mountains / USA; Vosges / France; Mexico; Brazil; Australia; India, Madagascar; Peru and New Zealand.
In the US state of Nevada, the city of Rhyolites was named after the rock found there.

Importance and use of rhyolite

Rhyolite is mainly used as a paving stone and curb stone as well as road gravel.
In addition, rhyolite is sold under the trade names Aztekenstein and Dr. Liesegang stone was sold as a healing stone without the healing properties of rhyolite being confirmed in clinical studies.

Rhyolite - Our recommendation *

Also interesting:
⇒ Thundereggs
⇒ The snow head balls from the Thuringian Forest
⇒ Rochlitz Porphyry - Rochlitz marble

⇒ Dove, H. W. (1847): The cycle of water on earth
⇒ Richthofen, F. v. and K. Peters (1859): Gebirgsarten. IN: Overview of the results of mineralogical research in the years 1856 and 1857
⇒ Bauer, J .; Tvrz, F. (1993): The Cosmos Mineral Guide. Minerals rocks precious stones. An identification book with 576 color photos. Gondrom Verlag GmbH Bindlach
⇒ Pellant, C. (1994): Stones and Minerals. Ravensburger nature guide. Ravensburger Buchverlag Otto Maier GmbH
⇒ Schumann, W. (1991): Minerals rocks - characteristics, occurrence and use. FSVO nature guide. BLV Verlagsgesellschaft mbH Munich
⇒ Maresch, W., Medenbach, O .; Trochim, H.-D. (1987): The colored natural guide rocks. Mosaik Verlag GmbH Munich *
⇒ Murawski, H. (1992): Geological Dictionary. Ferdinand Enke Verlag Stuttgart
⇒ Schumann, W. (1994): Collecting stones and minerals; find, prepare, determine. BLV Verlag Munich
⇒ Okrusch, M. and S. Matthes (2009): Mineralogy: An introduction to special mineralogy, petrology and deposit science. Springer Verlag Berlin Heidelberg

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