Pyroxene is most abundantly represented as crystals in many kinds of igneous and metamorphic rocks.
Always of secondary origin as a result of chemical alteration of certain other minerals, such as biotite-mica, pyroxene or amphibole.
One kind of jade is an amphibole similar to tremolite and actinolite in composition, while the other kind is a pyroxene (see below).
The most common variety of pyroxene is augite, a dark-green to black silicate of aluminum, iron, lime, and magnesia.
Their pyroxene is principally aegirine or aegirine augite; some of them are rich in melanite.
Pyroxene is the usual ferromagnesian mineral, and resembles that of the tephrites and basanites.
In the groundmass the felspar-lathes are in flow arrangement and the pyroxene is granular.
At one time a plate of pyroxene exhibits itself as a coarse aggregate of the two pyroxenes.
Pyroxene of the groundmass ophitic or semi-ophitic.
It will be noticed in the scheme that the “prismatic” sub-orders, where the pyroxene of the groundmass is for the most part in prisms, are scarcely represented.
The pyroxene prisms of the groundmass average ·01-·04 mm.
It is noticeable on account of the prismatic pyroxene of the groundmass; and it is assigned to genus 5 of the second (prismatic) sub-order of the hypersthene-augite andesites.
It is only at times that intergrowths of rhombic pyroxene occur.
In the groundmass the felspar-lathes are in flow-arrangement and the pyroxene is in great part prismatic.
In the others, where rhombic pyroxene is more predominant and where the felspar is less basic, it is 2·6 to 2·7.
The original hornblende phenocrysts are only represented by traces of pseudomorphs of fine pyroxeneand magnetite, the process of dispersion, described on page 307, being almost completed.
The pyroxene prisms of the groundmass are of the same yellowish augite.
This is especially the case in the Naivaka peninsula, where the rocks show a fair amount of glass in the groundmass, the porphyritic augite being well developed, whilst the pyroxene of the groundmass is only in part differentiated.
From the former they are distinguished by the great predominance of rhombic pyroxene both as phenocrysts and in the groundmass; whilst from the latter they are separated by the absence of brown hornblende or its pseudomorphs.
Pyroxene phenocrysts are not represented in the slide.
The principal minerals are, plagioclase, biotite and microcline, with smaller quantities of quartz, iron oxide, pyroxene and garnet.
A coarse dark green rock whose principal constituents are pyroxene plagioclase and magnetite.
There is also a small amount of hematite, pyroxene and sericite.
The change of pyroxene to amphibole by paramorphism.
Pyroxene is an essential constituent of many rocks, especially basic igneous rocks, as basalt, gabbro, etc.
A granular, crystalline, ingeous rock composed of orthoclase and hornblende, the latter often replaced or accompanied by pyroxene or mica.
Defn: A greenish spotted porphyry, being a diabase whose pyroxene has been altered to uralite; -- first found in the Pyreness.
Defn: An igneous rock consisting largely of chrysolite, withpyroxene and picotite (a variety of spinel containing chromium).
Defn: An orthorhombic mineral of the pyroxene group, of a grayish or greenish black color, often with a peculiar bronzelike luster (schiller) on the cleavage surface.
Defn: A variety of pyroxene of olive-green color passing into brown.
Defn: The change of pyroxene to amphibole by paramorphism.
Defn: Amphibole resulting from the alternation ofpyroxene by paramorphism.
An orthorhombic mineral of the pyroxene group, of a grayish or greenish black color, often with a peculiar bronzelike luster (schiller) on the cleavage surface.
A variety of pyroxene of olive-green color passing into brown.
An igneous rock consisting largely of chrysolite, withpyroxene and picotite (a variety of spinel containing chromium).
A greenish spotted porphyry, being a diabase whose pyroxene has been altered to uralite; -- first found in the Pyreness.
A dark-colored, basic, igneous rock, composed essentially of pyroxene and a triclinic feldspar with magnetic iron.
A mineral of the pyroxene group, orthorhombic in crystallization; often fibrous and massive; color grayish white or greenish.
Like talc it is usually developed within those igneous rocks from which feldspar is lacking, but where either pyroxene or olivine is found in abundance or was previous to alteration.
The pyroxene is often in part changed to fibrous amphibole.
A silicate of magnesium and hydroxyl which is an important alteration product through weathering of certain pyroxene rocks especially.
Amphibole and Pyroxene Group differ somewhat in their crystallisation form, though they all belong to the monoclinic system.
Segregations of iron ores, such as ilmenite, usually with pyroxene or olivine, occur in association with some gabbro and anorthosite masses.
In these the minerals have a parallel arrangement, the felspars are often broken down by pressure into a mosaic of irregular grains, while greenish fibrous or bladed amphibole takes the place of pyroxene and olivine.
Frequently the material is interlaminated with a rhombic pyroxene (bronzite) or with an amphibole (smaragdite or uralite), the latter being an alteration product of the diallage.
It is also an essential constituent of some pyroxene-granites, diorites and a few other igneous rocks, but the characteristic pyroxene of this class of rocks is augite.
Diopside is the characteristic pyroxene of metamorphic rocks, occurring especially in crystalline limestones, and often in association with garnet and epidote.
A mineral occurring in triclinic crystals approaching pyroxene in angle, and of a greenish black color.
It is a silicate of magnesia and iron, of thepyroxene family.
Usually the white crystals to be seen in an eruptive rock in contrast to the dark green or black of the pyroxene or hornblende, or the glassy, nearly colorless quartz, are Feldspar.
It occurs together with the form ofpyroxene known as hypersthene, in a coarse-grained granite, or perhaps a gneiss.
Pseudomorphs of amphibole after pyroxene are known as uralite.
In its crystallographic characters it is close to ordinary pyroxene (augite and diopside), being monoclinic and having nearly the same angle between the prismatic cleavages.
Their nucleus is almost as hard as basalt, and they are intermingled with little cavities, owing to bubbles of gas, filled with green earth, and crystals of pyroxene and mesotype.
I found no real basalt or dolerite; but the presence of pyroxene in the amygdaloid of Parapara leaves little doubt of the igneous origin of those spheroidal masses, fissured, and full of cavities.
After that, the form was found preserved in a third mineral, serpentine; and in one of the previous specimens it was then observed to pass continuously through two of the minerals, pyroxene and serpentine.
These masses of pyroxene may characterize a thickness of about 200 feet, and the interspaces among them are filled with a mixture of serpentine and carbonate of lime.
The calcareous septa in this specimen are very thin, and are transverse to the plane of contact of the two minerals; yet they are seen to traverse both the pyroxene and the serpentine without any interruption or change.
Even the pyroxene has been shown by Hunt to exist in the Laurentian in veins of aqueous origin.
The serpentine and pyroxene which fill the cavities of the calcareous matter have no appearance of concretionary structure.
Further, how does it happen that in some specimens serpentine and pyroxene seem to have encroached upon the structure, as if they and not calcite were the eroding minerals?
The calcite, dolomite, and pyroxene exhibit their crystalline structure to the unaided eye; and the serpentine and loganite are also seen to be crystalline when examined with the microscope.
This is the more remarkable as pyroxene is most usually found as an ingredient of igneous rocks; but Dr.
The laminæ of serpentine and pyroxene present no organic structure, and the latter mineral is highly crystalline.
Small irregular veins of crystalline calcite, and of serpentine, are found to traverse such pyroxene masses in the Eozoon limestone of Grenville.
Serpentine andpyroxene are generally associated in these specimens, as if their disposition had marked different stages of a continuous process.
It is in some layers pure and white, in others it is traversed by many gray layers of gneissose and other matter, or by irregular bands and nodules of pyroxene and serpentine, and it contains subordinate beds of dolomite.
The pyroxene in particular is very much changed, and quickly crumbles away in the hand.
This loose material when carefully examined is found to be made up of exactly the same minerals as the dense rock below, but we notice that the mica and pyroxene are rusty and that the feldspar is stained yellowish brown.
The greyish blue amygdaloid contains fendilated crystals of pyroxene and mesotype.
The above list will hopefully give you a few useful examples demonstrating the appropriate usage of "pyroxene" in a variety of sentences. We hope that you will now be able to make sentences using this word. Other words: alabaster; asphalt; mineral
