Which of the following best describes a basalt?

Answer: 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 the texture of basalt?

Basalt is the volcanic equivalent of gabbro. Group – volcanic. Colour – dark grey to black. Texture – aphanitic (can be porphyritic).

What is the composition of basalt?

Basalt generally has a composition of 45–52 wt% SiO2, 2–5 wt% total alkalis, 0.5–2.0 wt% TiO2, 5–14 wt% FeO and 14 wt% or more Al2O3. Contents of CaO are commonly near 10 wt%, those of MgO commonly in the range 5 to 12 wt%.

Is diorite acidic or basic?

Basic rocks such as gabbro, dolerite and basalt are poor in silica and contain the minerals olivine, pyroxene, feldspar and/or quartz among others; they are also rich in the metals magnesium and iron and are often described as “mafic”. The intermediate rocks include diorite, microdiorite and andesite.

What causes basalt columns?

These columns of rock are most likely a volcanic rock called basalt. (Basalt makes up about 90% of all the lava rock on Earth.) In this case, the lava starts to crack into regular shapes. Those shapes are forming because of how the lava cools.

Why are hexagonal basalt columns?

Basalt columns with their preferably hexagonal cross sections are a fascinating example of pattern formation by crack propagation. Junctions of three propagating crack faces rearrange such that the initial right angles between them tend to approach 120°, which enables the cracks to form a pattern of regular hexagons.

Why do they call it the Giant’s Causeway?

It does, however, attract some 300,000 tourists annually. Deriving its name from local folklore, it is fabled to be the work of giants, particularly of Finn MacCumhaill (MacCool), who built it as part of a causeway to the Scottish island of Staffa (which has similar rock formations) for motives of either love or war.

Is Iceland made of basalt?

Since Iceland consists for 90% of basalt, let’s talk about this rock type first. Basalt is a dark grey or black rock, sometimes having a columnar structure, formed by solidification of magma. It can be dense or fine-grained and usually consists of plagioclase, augite and magnetite. Basalt is not unique to Iceland.

Why are hexagons the most efficient shape?

A hexagon is the shape that best fills a plane with equal size units and leaves no wasted space. Hexagonal packing also minimizes the perimeter for a given area because of its 120-degree angles.

What is the most efficient shape for area?

History of the Efficient Shape Problem

Of all regular polygons with equal perimeter, the one with the most sides has the greatest area.
A circle has a greater area than any regular polygon of the same perimeter.
A sphere has a greater volume than solid figures with the same surface area.

Which of the following best describes a basalt?

What type of igneous rock is basalt?

Basalt is a mafic extrusive rock, is the most widespread of all igneous rocks, and comprises more than 90% of all volcanic rocks. Because of its relatively low silica content, basalt lava has a comparatively low viscosity, and forms thin flows that can travel long distances.

Which of the following is a volcanic igneous rock?

When magma does reach the surface during a volcanic eruption, the rocks that form there are called lavas or volcanic rocks. The basic classification is the same as for plutonic rocks: with increasing silica content, they include: basalt, andesites, dacites, rhyolite, pumice and obsidian.

What are volcanic rocks called?

Volcanic rock (also called extrusive rock) is one type of magmatic rock (igneous rocks) and is the condensated product of extrusive magma after diagenesis and compaction, which differ greatly from sedimentary rocks in forming conditions, environments, and distribution.

Do diamonds melt in lava?

The melting point of Diamond at about 100,000 atm is 4200 K, which is much higher than the temperature of lava. So, it is impossible for lava to melt a diamond. So, if the temperature of lava is above this, the diamond will burn (not melt).

Do volcanic rocks have oxygen?

The liquid “freezes” to form volcanic glass. Chemically lava is made of the elements silicon, oxygen, aluminum, iron, magnesium, calcium, sodium, potassium, phosphorus, and titanium (plus other elements in very small concentrations. Have a look at the background information in Minerals, Magma, and Volcanic Rocks.

Do volcanic rocks have carbon?

Given enough time, that carbon, in the form of diamonds, rocks, or as carbon dioxide emissions emitted from volcanoes, returns to the surface, where the sun shines on it once more. This disruption of the carbon cycle is what we are calling the climate crisis, says Hazen.

Do volcanic rocks have magnesium?

Volcanic rocks, which cool quickly above ground, have small crystals because the crystals did not have enough time to grow very large. Felsic igneous rocks contain relatively high amounts of silicon, sodium, aluminum, potassium (Si, Na, Al, and K) and relatively low amounts of iron, magnesium, and calcium (Fe, Mg, Ca).

Does Magma contain oxygen?

Oxygen, the most abundant element in magma, comprises a little less than half the total, followed by silicon at just over one-quarter. The remaining elements make up the other one-quarter. Magmas derived from crustal material are dominated by oxygen, silicon, aluminum, sodium, and potassium.

Which component of magma is the highest and lowest in value?

Felsic magma has the highest silica content of all magma types, between 65-70%. As a result, felsic magma also has the highest gas content and viscosity, and lowest mean temperatures, between 650o and 800o Celsius (1202o and 1472o Fahrenheit).

Is Magma hotter than lava?

Magma is hotter than lava, depending on how recently the lava reached the surface and if the magma and lava are from the same magma chamber below the…

What are the three types of magma?

There are three basic types of magma: basaltic, andesitic, and rhyolitic, each of which has a different mineral composition. All types of magma have a significant percentage of silicon dioxide. Basaltic magma is high in iron, magnesium, and calcium but low in potassium and sodium.

Which type of magma is most explosive?

andesitic

What are the 4 characteristics of magma?

Magma (Characteristics, Types, Sources, and Evolution) A magma consists mostly of liquid rock matter, but may contain crystals of various minerals, and may contain a gas phase that may be dissolved in the liquid or may be present as a separate gas phase.

What type of magma has the highest viscosity?

rhyolitic magma

Why does silica increase viscosity?

In other words, as magma cools, its viscosity increases. This property is increased by crystallization of magma while temperature decreases. Finally, the composition of a magma highly affects its viscosity. A higher concentration in silica leads to a more acid/more viscous magma.

How does viscosity affects the movement of magma?

High viscosity lavas flow slowly and typically cover small areas. In contrast, low viscosity magmas flow more rapidly and form lava flows that cover thousands of square kilometers.

Does temperature affect viscosity?

The gas viscosity will increase with temperature. The result is that liquids show a reduction in viscosity with increasing temperature. With high temperatures, viscosity increases in gases and decreases in liquids, the drag force will do the same.

How does viscosity depend on temperature?

In general, the viscosity of a simple liquid decreases with increasing temperature. While liquids get runnier as they get hotter, gases get thicker. (If one can imagine a “thick” gas.) The viscosity of gases increases as temperature increases and is approximately proportional to the square root of temperature.

Does temperature has any effect on viscosity give two examples to justify your statement?

Viscosity depends strongly on temperature. In liquids it usually decreases with increasing temperature, whereas, in most gases, viscosity increases with increasing temperature.

What causes viscosity to increase?

For most liquids, viscosity increases with increasing pressure because the amount of free volume in the internal structure decreases due to compression. Consequently, the molecules can move less freely and the internal friction forces increase. The result is an increased flow resistance.

Which of these fluids has the highest viscosity?

For instance, honey has a much higher viscosity than water. Viscosity is measured using a viscometer. Measured values span several orders of magnitude. Of all fluids, gases have the lowest viscosities, and thick liquids have the highest.

Which has higher viscosity water or mercury?

On the other hand, the cohesive forces between mercury atoms are much greater than the adhesive forces between mercury and glass….7.1: Surface Tension, Viscosity, and Capillary Action.

Substance	Formula	Viscosity (mPa·s)
water	H2O	0.890
mercury	Hg	1.526
ethanol	C2H5OH	1.074
octane	C8H18	0.508

Does Mercury have a high viscosity?

Stronger forces between particles give higher surface tension, and usually also higher viscosity. Most strikingly, mercury has really extraordinarily high surface tension, but is no more viscous than cold water.