Pyroxenes crystallizing in the monoclinic system are the most important.
Along with quartz and feldspars, the pyroxenes rank among the most common of all minerals.
This rock displays a few small phenocrysts of oligoclase and pyroxenes in a blurred glassy groundmass exhibiting the felspar and pyroxene microliths in process of development (sp.
Finally follows the dispersion of the pseudomorph, which first becomes a loosely arranged aggregate of the two pyroxenes and magnetite, and then breaks down, and at length is only represented by small pale patches of its original constituents.
But when, as is generally the case, the pyroxenes are more frequent, it occurs as a dark grey mass.
The association of the two pyroxenes in one crystal can in some cases be clearly recognised.
There is a slight tendency to semi-ophitic behaviour in places; but generally these pyroxenes are irregular in shape or rudely prismatic.
The prismatic pyroxenes of the groundmass vary in average length from ·03 to ·08 mm.
The pyroxenes of the groundmass are similarly coarse (·2 mm.
Where the alteration is less advanced small parallel felspar-lathes with fine decomposing pyroxenes are shown.
It also shows abundant small pyroxenes in the form of small prisms (·05 mm.
With the Kandavu rocks Renard observed that the tiny pyroxenes were colourless or greenish and had an extinction angle of 40°.
There can be little doubt that this is the source of much at least of the often abundant pyroxenes of the groundmass, which are usually most frequent in the vicinity of the patches.
The augite is less frequent, but the two pyroxenes are sometimes associated as intergrowths.
In Moraine Park gray andesites also predominate, with both pyroxenes as phenocrysts, but here hypersthene is the more important.
Of the darker phenocrysts, the pyroxenes are more abundant than the olivine or hornblende.
Like the other pyroxenes it is characterized crystallographically by its distinct cleavages parallel to the prism-faces (M), the angle between which is 87 deg.
The above list will hopefully give you a few useful examples demonstrating the appropriate usage of "pyroxenes" in a variety of sentences. We hope that you will now be able to make sentences using this word.
