What is basanite made of?
What is basanite made of?
basanite, extrusive igneous rock that contains calcium-rich plagioclase feldspar (usually labradorite or bytownite), feldspathoid (usually nepheline or leucite), olivine, and pyroxene (titanaugite).
Where is basanite found?
Basanite appears early in the alkaline magma series and basanites are found wherever alkaline magma is erupted. This includes both continental and ocean island settings. Together with basalts, they are produced by hotspot volcanism, for example in the Hawaiian Islands, the Comoros Islands and the Canary Islands.
Is basanite a basalt?
Essentially, the mineralogy is that of a basalt, with the addition of a feldspathoid mineral and olivine. Varieties of basanites are defined by the type of feldspathoid mineral present to give nepheline-basanite, analcite-basanite, and leucite-basanite.
Which type of Lustre is exhibited by nepheline?
vitreous lustre
Nepheline is an important feldspathoid mineral. It is white, grey or yellow in colour with a vitreous lustre and a poor cleavage.
What is andesite good for?
Andesite is currently used only for decoration. It has the same blast resistance as stone, meaning it can be used as a substitute for stone when building.
What is the use of quartzite rock?
Quartzite is use for making bricks and other strong building materials. It is also growing in popularity as a decorative stone, and has a limited use as crushed stone. As it is so hard, quartzite is not quarried as much as softer stone, and tends to be taken from the surface rather than underground.
How can you identify a nepheline in a thin section?
Nepheline is colorless under plane polarized light in thin section. Click on the image to see the crystal under crossed polars. This hexagonal crystal is oriented with its optic axis vertical.
What is the difference between basanite and nephelinite?
Chemically, basanites are mafic. They are low in silica (42 to 45% SiO 2) and high in alkalis (3 to 5.5% Na 2 O and K 2 O) compared to basalt, which typically contains more SiO 2, as evident on the diagram used for TAS classification. Nephelinite is yet richer in Na 2 O plus K 2 O compared to SiO 2 .
What is the mineral assembly of basanite?
The mineral assembly in basanite is usually abundant feldspathoids ( nepheline or leucite ), plagioclase, and augite, together with olivine and lesser iron-titanium oxides such as ilmenite and magnetite – ulvospinel; minor alkali feldspar may be present. Clinopyroxene ( augite) and olivine are common as phenocrysts and in the matrix.
What is the difference between quartz and basanite?
Quartz is absent, as are orthopyroxene and pigeonite. Chemically, basanites are mafic. They are low in silica (42 to 45% SiO 2) and high in alkalis (3 to 5.5% Na 2 O and K 2 O) compared to basalt, which typically contains more SiO 2, as evident on the diagram used for TAS classification.
