Another group is rich in quartz ( quartzites, quartz schists and quartzose gneisses ), with variable amounts of white and black mica, garnet, feldspar, zoisite and hornblende.

The first group includes principally schists and quartz-feldspar, greywackes and quartzites with meta-crystals, such as Andalusite, Cordierite and Sillimanite.

In his many contributions to scientific journals he described the granulite group, and dealt with pegmatites, variolites, eurites, the ophites of the Pyrenees, the extinct volcanoes of Central France, gneisses, and the origin of crystalline schists.

At Glen Tilt in the Cairngorm mountains in the Scottish Highlands in 1785, Hutton found granite penetrating metamorphic schists, in a way which indicated that the granite had been molten at the time.

It also occurs in metamorphic rocks such as gneiss and schists and skarns.

At Glen Tilt in the Cairngorm mountains he found granite penetrating metamorphic schists, in a way which indicated to him that the presumed primordial rock had been molten after the strata had formed.

Almandine occurs in metamorphic rocks like mica schists, associated with minerals such as staurolite, kyanite, andalusite, and others.

Most schists have been derived from clays and muds which have passed through a series of metamorphic processes involving the production of shales, slates and phyllites as intermediate steps.

The graphitic schists may readily be believed to represent sediments once containing coal or plant remains ; there are also schistose ironstones ( hematite-schists ), but metamorphic beds of salt or gypsum are exceedingly uncommon.

Rock types in the mountains are typically granites and metamorphic schists, and some are highly sheared near to fault zones.

Tremolite, while it is a metamorphic amphibole, is derived most usually from highly metamorphosed ultramafic rocks, and thus tremolite-talc schists are not generally considered as ' amphibolites '.

Actinolite schists are often the result of hydrothermal alteration or metasomatism, and thus may not, necessarily, be a good indicator of metamorphic conditions when taken in isolation.

Another theory of the black and white colours is that the white cross represents the igneous / metamorphic rocks of colour such as granite and schists mainly found in the southwest of Cornwall, while the black background represents the weathered Devonian slate and Carboniferous sandstone, both of which are mainly black-greyish in appearance, of the northern part of Cornwall.

As in nearby Caithness, these rocks rest upon the metamorphic rocks of the eastern schists, and in Mainland where a narrow strip is exposed between Stromness and Inganess, they are represented by grey gneiss and granite.

The rocks here were mashed up when the Pyrenees ( or Pirineus in Catalan ) were formed, and are mostly metamorphic schists which turn a golden colour in the Mediterranean sun.

Early Proterozoic, metamorphic rocks consist of schists and amphibolites.

The Centre's soil is primarily composed of Precambrian deposits of metamorphic rocks, such as gneiss, mica, migmatites, and schists.

Faults along the border with the South Province have deposited metamorphic schists and quartzites, with some granite.

Scapolite is commonly a mineral of metamorphic origin, occurring usually in crystalline marbles, but also with pyroxene in schists and gneisses.

The Gotel and Mambila Mountains at the border with Nigeria are largely composed of granite, which gives way to crystalline and metamorphic rock such as mica, schists, and gneiss.

Much of the route follows the contact point between the igneous granite of the western side of Wicklow and the metamorphic schists and slates of the eastern side.

The structure of the soil also differs considerably from other wine growing regions of the country, with heavy deposits of rough-edged mica and other metamorphic schists in silt loams.

It is essentially metamorphic and occurs with gneisses, schists and granulites, especially in the Scandinavian peninsula, where it is regarded as being very characteristic of certain horizons.

The subsoils are made-up of essentially granular schists, greywacke, sandstone, and in some areas quartzite, as well as rare volcanic metamorphic particulates with reduced permeability.

Faults tentatively follow the Bénoué River north of this and form a barrier to split the remainder of the province, with metamorphic rocks such as gneiss, mica, and schists dominating to the south and sedimentary stone making up the north.

Some areas within the wilderness display bedrock composed of metamorphic schists with large garnet crystals.

The rock is primarily metamorphic: marble and limestone formed from rocks originating in the Mesozoic, crystalline schists formed from rocks originating in the Palaeozoic and conglomerates of the Cenozoic.

Between the Cotton Belt and the Tennessee Valley is the mineral region, the Old Land area — a region of resistant rocks — whose soils, also derived from weathering in silu, are of varied fertility, the best coming from the granites, sandstones and limestones, the poorest from the gneisses, schists and slates.

Andradite is found both in deep-seated igneous rocks like syenite as well as serpentines, schists, and crystalline limestone.

Certain schists have been derived from fine-grained igneous rocks such as basalts and tuffs.

During metamorphism, rocks which were originally sedimentary or igneous are converted into schists and gneisses.

For that reason many of these rocks split readily in one direction along mica-bearing zones ( schists ).

Rocks that were originally sedimentary and rocks that were undoubtedly igneous may be metamorphosed into schists and gneisses.

The more completely altered forms of these rocks are platy, green chloritic schists ; in these, however, structures indicating their original volcanic nature only sparingly occur.

It was formed by granite and gneiss rocks and crystal schists during the Paleozoic ( 250, 000, 000 years ago ).

* Banno, S. " Glaucophane schists and associated rocks in the Ōmi District, Niigata Prefecture, Japan ".

In his published papers he dealt with metamorphism and crystalline schists, discussed the origin of serpentine, and wrote on the rocks Mount Vesuvius and Ponza Island.

Above the broad and deep accumulations of the products of denudation which have been brought down by the rivers from the Tian Shan ranges ( e. g. the Karlyk-tagh ) on the north and from the Nanshan on the south, and have filled up the cauldron-shaped valleys, there rises a broad swelling, built up of granitic rocks, crystalline schists and metamorphosed sedimentary rocks of both Archaic and Palaeozoic age, all greatly folded and tilted up, and shot through with numerous irruptions of volcanic rocks, predominantly porphyritic and dioritic.

They can contain a very great variety of minerals, the principal ones being quartz, orthoclase and plagioclase feldspars, calcite, iron oxides and graphitic, carbonaceous matters, together with ( in the coarser kinds ) fragments of such rocks as felsite, chert, slate, gneiss, various schists, and quartzite.

It should be remembered that though granulites are probably the commonest rocks of this country, they are mingled with granites, gneisses, gabbros, amphibolites, mica schists and many other petrographical types.

While searching for aluminous schists in Wyoming, geologist Dan Hausel noted an association of vermiculite with ruby and sapphire and located six previously undocumented deposits.

The chief geological investigation of the last decade of his life was devoted to the Highlands of Scotland, where he wrongly believed he had succeeded in showing that the vast masses of crystalline schists, previously supposed to be part of what used to be termed the Primitive formations, were really not older than the Silurian period, for that underneath them lay beds of limestone and quartzite containing Lower Silurian ( Cambrian ) fossils.

Ōmi is world famous for its glaucophane schists and calcareous deposition ( especially limestone ), as well as jadeite.

Gneiss and chlorite schists which are available throughout the district are frequently used for building purposes.