Trachyte in the context of "Antimilos"

Syenite is a coarse-grained intrusive igneous rock with a general composition similar to that of granite, but deficient in quartz, which, if present at all, occurs in relatively small concentrations (< 5%). It is considered a granitoid. Some syenites contain larger proportions of mafic components and smaller amounts of felsic material than most granites; those are classed as being of intermediate composition.

The extrusive equivalent of syenite is trachyte.

The Big Raven Plateau is an intermontane plateau in Cassiar Land District of northwestern British Columbia, Canada. It lies on the Tahltan Highland and is surrounded by several valleys, including those of Mess Creek, Kakiddi Creek, Chakima Creek, Walkout Creek and the Klastline River. The plateau is drained by many small streams that flow into these neighbouring valleys and, unlike the neighbouring valleys, it is relatively barren of vegetation. Stream erosion has resulted in the creation of canyons with intervening ridges on the eastern and western sides of the Big Raven Plateau. The plateau is in Mount Edziza Provincial Park, which is one of the largest provincial parks in British Columbia. Access to the Big Raven Plateau is mainly by aircraft or by a network of horse trails from surrounding roads.

The Big Raven Plateau is volcanic in origin, consisting mostly of basaltic lava flows of the Mount Edziza volcanic complex that were erupted in the last 7.5 million years. These lava flows are interbedded with rhyolite and trachyte which are in the form of rock fragments produced and ejected by explosive eruptions. The dominant feature on the Big Raven Plateau is Mount Edziza, an ice-covered stratovolcano reaching an elevation of 2,786 metres (9,140 feet). Its composition is more diverse, consisting of alkali basalt, hawaiite, trachybasalt, tristanite, mugearite, benmoreite, trachyte and rhyolite which are in the form of lava flows, lava domes and breccia. The Big Raven Plateau is subdivided into at least 10 geological formations, each being the product of a distinct period of volcanic activity.

Sanidine is the high temperature form of potassium feldspar with a general formula K(AlSi₃O₈). Sanidine is found most typically in felsic volcanic rocks such as obsidian, rhyolite and trachyte. Sanidine crystallizes in the monoclinic crystal system. Orthoclase is a monoclinic polymorph stable at lower temperatures. At yet lower temperatures, microcline, a triclinic polymorph of potassium feldspar, is stable.

Due to the high temperature and rapid quenching, sanidine can contain more sodium in its structure than the two polymorphs that equilibrated at lower temperatures. Sanidine and high albite constitute a solid solution series with intermediate compositions termed anorthoclase. Exsolution of an albite phase does occur; resulting cryptoperthite can best be observed in electron microprobe images.

The Monti della Tolfa (or Tolfa Mountains) are a volcanic group in the Anti-Apennines of the northern part of the Lazio region of Central Italy. They are bounded by the Tyrrhenian Sea coast to the west, by the Monti Sabatini to the east, and by the Monti Cimini and the Mignone river to the north. Tolfa and Allumiere are the principal towns.

The highest peak is the Monte Maggiore (633 m above sea level). The Monti della Tolfa consists mostly of trachytes formed during the Eocene and the early Pleistocene.

Mount Murphy (75°20′S 110°44′W / 75.333°S 110.733°W / -75.333; -110.733 (Mount Murphy)) is a snow-covered mountain with steep, rocky slopes rising to 2,634 metres (8,642 ft) in Marie Byrd Land, Antarctica.It is directly south of Bear Peninsula and is bounded by Smith Glacier, Pope Glacier, and Haynes Glacier.Volcanic activity began in the Miocene with the eruption of basaltic and trachytic lava. Volcanism on the slopes of the volcano resumed much later during the Pleistocene, with a parasitic cone having been K–Ar dated to 0.9 million years old.

Mount Edziza (/ədˈzaɪzə/ əd-ZY-zə; Tahltan: Tenh Dẕetle [ten̥ ˈdðetle]) is a volcanic mountain in Cassiar Land District of northwestern British Columbia, Canada. It is located on the Big Raven Plateau of the Tahltan Highland which extends along the western side of the Stikine Plateau. Mount Edziza has an elevation of 2,786 metres (9,140 feet), making it the highest point of the Mount Edziza volcanic complex and one of the highest volcanoes in Canada. However, it had an elevation of at least 3,396 m (11,142 ft) before its formerly cone-shaped summit was likely destroyed by a violent eruption in the geologic past; its current flat summit contains an ice-filled, 2-kilometre-in diameter (1.2-mile) crater. The mountain contains several lava domes, cinder cones and lava fields on its flanks, as well as an ice cap containing several outlet glaciers which extend to lower elevations. All sides of Mount Edziza are drained by tributaries of Mess Creek and Kakiddi Creek which are situated within the Stikine River watershed.

Mount Edziza consists of several types of volcanic rocks and at least six geological formations that formed during six distinct stages of volcanic activity. The first stage 1.1 million years ago produced basalt flows and a series of rhyolite and trachyte domes. Basalt flows and smaller amounts of trachyte, tristanite, trachybasalt, benmoreite and mugearite produced during the second stage about 1 million years ago comprise Ice Peak, a glacially eroded stratovolcano forming the south peak of Mount Edziza. The third and fourth stages 0.9 million years ago created basalt ridges and the central trachyte stratovolcano of Mount Edziza, respectively. Thick trachyte flows were issued during the fifth stage 0.3 million years ago, most of which have since eroded away. The sixth stage began in the last 20,000 years with the eruption of cinder cones, basalt flows and minor trachyte ejecta. Renewed volcanism could block local streams with lava flows, disrupt air traffic with volcanic ash and produce floods or lahars from melting glacial ice.

Trachybasalt is a volcanic rock with a composition between trachyte and basalt. It resembles basalt but has a high content of alkali metal oxides. Minerals in trachybasalt include alkali feldspar, calcic plagioclase, olivine, clinopyroxene and likely very small amounts of leucite or analcime.

Latite is an igneous, volcanic rock, with aphanitic-aphyric to aphyric-porphyritic texture. It is the volcanic equivalent of monzonite. Its mineral assemblage is usually alkali feldspar and plagioclase in approximately equal amounts. Quartz is less than five percent and is absent in a feldspathoid-bearing latite, and olivine is absent in a quartz-bearing latite. When quartz content is greater than five percent the rock is classified as quartz latite. Biotite, hornblende, pyroxene and scarce olivine or quartz are common accessory minerals. Feldspathoid-bearing latite is sometimes referred to as tristanite.

Rhomb porphyries are an unusual variety with gray-white porphyritic, rhomb-shaped phenocrysts embedded in a very fine grained red-brown matrix. The composition of rhomb porphyry places it in the trachyte - latite classification of the QAPF diagram.