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No. If a a rock is "aphanitic" it means that it is so fine-grained that it is impossible to tell which minerals are present in the matrix. The magma itself is not aphanitic. It is the rapid cooling of the magma that inhibits crystal growth and in turn make the rock's matrix aphanitic. Aphanitic rocks are commonly porphyric. Example: A diabase intrusion can be aphantic with white phenocrystals. Intrusions are often more aphanitic near the contact boundary of the rock that is being intruded. This is because the magma cools more rapidly near the cool, pre-existing rock and the crystals there have less time to grow than those in the middle of the intrusion.
What else can I help you with?
What is the grain size of a fine grained igneous rock?
The individual grains (crystals) in quickly cooled magma are described as aphanitic--not visible without magnification.
Does obsidian rock contain few or no mineral grains?
Obsidian is a type of volcanic glass that lacks a crystalline structure, so it does not contain mineral grains. It forms from quickly cooling lava rich in silica, resulting in a smooth, glassy texture without distinct mineral crystals.
When water combines with mineral grains do the grains become smaller or larger?
When water combines with mineral grains, the grains can become smaller due to mechanical weathering processes like abrasion and attrition, where the movements of water cause the grains to break down into smaller pieces. However, in some cases, water can also facilitate processes like dissolution or precipitation that can lead to mineral grains growing larger.
Is it true that most lava crystallizes to form igneous rocks with phaneritic textures?
No, not all lava crystallizes to form igneous rocks with phaneritic textures. Phaneritic textures are characterized by large, visible crystals, which form when magma cools slowly beneath the Earth's surface. Lava that cools quickly on the Earth's surface forms igneous rocks with aphanitic textures, characterized by fine-grained or glassy structures.
What are mineral grains made up of?
Mineral grains are crystals or pieces of crystals that vary widely in chemical composition. There are over 4,000 different minerals that have been identified so far.
What igneous rock is aphanitic texture?
These are igneous rocks that are too fine textured to an extent that there mineral grains or crystalline texture cannot be seen or distinguished with the necked or unaided eyes. They appear or occur as a whole single massive crystalline extrusive body of Igneous origin. Example is Obsidian.
A rock that cools very quickly so that few or no mineral grains form is?
You can describe the rock by the process that allowed it to cool quickly: "Extrusive" or you can describe it by its texture: "aphanitic". An extrusive rock tends to be aphanitic = Rocks formed from lava flows tend to have small crystals.
What is the grain size of a fine grained igneous rock?
The individual grains (crystals) in quickly cooled magma are described as aphanitic--not visible without magnification.
Does pumic have mineral grains?
Pumice does not have grains.
Small grained rocks have what texture?
Fine grained rocks are considered aphanitic.
What is a term that describes an igneous rock texture in which crystals are present but are not visible?
A term that describes an igneous rock texture with crystals that are present but not visible would be aphanitic. This texture indicates that the individual mineral grains are too small to be distinguished with the naked eye.
How is the size of the mineral grains affect by the rate at which molten rock material rock?
The slower the rate of cooling the larger the size of the crystals that can develop.
Does obsidian rock contain few or no mineral grains?
Obsidian is a type of volcanic glass that lacks a crystalline structure, so it does not contain mineral grains. It forms from quickly cooling lava rich in silica, resulting in a smooth, glassy texture without distinct mineral crystals.
When water combines with mineral grains do the grains become smaller or larger?
When water combines with mineral grains, the grains can become smaller due to mechanical weathering processes like abrasion and attrition, where the movements of water cause the grains to break down into smaller pieces. However, in some cases, water can also facilitate processes like dissolution or precipitation that can lead to mineral grains growing larger.
Is it true that most lava crystallizes to form igneous rocks with phaneritic textures?
No, not all lava crystallizes to form igneous rocks with phaneritic textures. Phaneritic textures are characterized by large, visible crystals, which form when magma cools slowly beneath the Earth's surface. Lava that cools quickly on the Earth's surface forms igneous rocks with aphanitic textures, characterized by fine-grained or glassy structures.
What changes mineral grains into rock without melting them?
They can be "cemented" as some mineral such as calcite, aragonite, hematite, or even silica precipitates out of solution between them. Or clay minerals between the grains can harden under pressure and heat well short of their melting point.
What rock has large mineral grains?
Fine grains of rocks are referred to as "clasts." The word "clast" comes from the Greek word "klastos," meaning "broken."
