What is the best description of basalt?
Basalt is a dark-colored, fine-grained, igneous rock composed mainly of plagioclase and pyroxene minerals. It most commonly forms as an extrusive rock, such as a lava flow, but can also form in small intrusive bodies, such as an igneous dike or a thin sill. It has a composition similar to gabbro.
What is basalt rock texture?
Basalts have almost always aphanitic or fine-grained mineral texture resulting from rapid cooling of volcanic magma.
What is the colour of basalt?
dark grey to black
Basalt is the volcanic equivalent of gabbro. Group – volcanic. Colour – dark grey to black.
What type of rocks is basalt?
Basalt is a hard, black volcanic rock. Basalt is the most common rock type in the Earth’s crust. Depending on how it is erupted, basalt can be hard and massive (Figure 1) or crumbly and full of bubbles (Figure 2).
Can basalt be smooth?
Basalt is the only rock-like block to have both a polished and smooth variant.
What is the composition of basalt rock?
Basalt is rich in iron and magnesium and is mainly composed of olivine, pyroxene, and plagioclase. Most specimens are compact, fine-grained, and glassy. They can also be porphyritic, with phenocrysts of olivine, augite, or plagioclase. Holes left by gas bubbles can give basalt a coarsely porous texture.
Is basalt a hard stone?
Basalt is a wonderfully hard natural stone, and one of the most abundant rocks on Earth.
Does basalt have a rough texture?
‘A’a basalts have rough surfaces (that make barefoot people cry, “Ah! Ah!” as they walk across it). They form from fast flowing lava. Pahoehoe basalts have a smooth glassy surface that looks like many ropes.
Is basalt rock heavy?
Not all volcanic rock is ‘light’ or low density — basalt is relatively heavy and is organic, granite is lighter, but still volcanic in origin.
What does basalt rock feel like?
Feel its texture. Basalt consists of a fine and even-grain. The dense rock has no crystals or minerals discernible to the naked eye. When freshly broken, basalt has a dull surface.
Can basalt float on water?
If there’s enough air trapped, the volcanic rock *could* float on water — but the vast majority will sink, just like any other rock. Hope this helps! Answer 3: Not all volcanic rock is ‘light’ or low density — basalt is relatively heavy and is organic, granite is lighter, but still volcanic in origin.
Is Basalt porous or nonporous?
Porosity and strength: As a result of its density and mineral makeup, basalt is both highly non-porous and strong.
Does basalt float in water?
What are the physical properties of basalt?
Tholeiitic basalt is relatively rich in iron and poor in alkali metals and aluminium.
What types of rocks are basalt and granite?
What are the different types of basalt?
– Tholeiite (oversaturated): contains normative hypersthene and quartz – Tholeiite (saturated): contains normative hypersthene, but no quartz – Olivine tholeiite: contains normative hypersthene and olivine – Olivine basalt: contains normative olivine, but no normative hypersthene or nepheline – Alkali basalt: contains normative olivine and nepheline
Is basalt an igneous rock?
Basalt is an igneous rock that contains more than 45 and less than 52% of SiO2 and less than five percent of total alkalies (K2O + Na2O)3. Tholeiitic basalt is relatively rich in silica and poor in sodium.