Glossary of Rock and Mineral Terms - V
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- valley glacier
- An alpine glacier that flows through a preexisting stream valley.
- Group of minerals that are compounds of one or more metallic element
associated with the vanadate radical (VO4). The vanadates, together
with the related arsenates, are classified in the phosphate group. Most
vanadates are heavy, and none are hard. They are usually brittle and occur in
small crystals or compact aggregates.
- van der Waals bond
- A relatively weak kind of intermolecular bond that forms when one
side of a molecule develops a slight negative charge because a number of electrons
have temporarily moved to that side of the molecule. This negative charge
attracts the nuclei of the atoms of a neighboring molecule. The
side of the molecule with fewer electrons develops a slight positive charge
that attracts the electrons of the atoms of neighboring molecules.
- variable formula
- Chemical formula of a mineral that includes all common elemental
replacements. For example, the mineral Adamite - Zn2(AsO4)(OH),
frequently contains part of the zinc (Zn) replaced by copper (Cu) or cobalt
(Co); thus its variable formula is (Zn,Cu,Co)2(AsO4)(OH).
- Titled variable of a mineral, characterized by a special property not
present in other members of that same mineral such as color, location,
chemical additive, crystal or aggregate, etc.
- A pair of sediment beds deposited by a lake on its floor, typically
consisting of a thick, coarse, light-colored bed deposited in the summer and a
thin, fine-grained, dark-colored bed deposited in the winter. Varves are most
often found in lakes that freeze in the winter. The number and nature of
varves on the bottom of a lake provide information about the lake's age and
geologic events that affected the lake's development.
- A long, thin section of a mineral, usually in fibrous form, embedded in
rock, called the surrounding rock. Usually caused by the filling in of the
mineral in open spaces or cracks in the rock
- An opening in the Earth's surface through which lava, gases, and hot
particles are expelled. Also called volcanic vent and volcano.
Venting is The escaping of hot gases or lava from the crust of the earth.
- A stone that has been flattened and sharpened by wind abrasion. Ventifacts
are commonly found strewn across a desert floor.
- verneuil process
- The course of creating synthetic gems from molten solutions and letting them
form into boules.
- A fluid's resistance to flow. Viscosity increases as temperatures decrease.
- vitreous luster
- Luster describing minerals with reflective properties similar to that of
- Synonym of sulfuric acid.
- Disappear as fumes.
- Having originated from a volcano.
- volcanic arc
- A chain of volcanoes fueled by magma that rises from an underlying subducting
- volcanic cone
- A cone-shaped mountain that forms around a vent from the debris of pyroclastics
and lava ejected by numerous eruptions over time.
- volcanic crater
- A steep, bowl-shaped depression surrounding a vent. A volcanic crater
forms when the walls of a vent collapse inward following an eruption.
- volcanic dome
- A bulb-shaped solid that forms over a vent when lava so viscous
that it cannot flow out of the volcanic crater cools and hardens. When
a volcanic dome forms, it traps the volcano's gases beneath it. They either
escape along a side vent of the volcano or build pressure that causes another
eruption and shatters the volcanic dome.
- volcanic rock
- Rock formed as a direct result of a volcano, the solidifying of magm). See extrusive rock.
- The set of geological processes that result in the expulsion of lava,
pyroclastics, and the volcanic venting effects associated with volcanoes:
hot springs, smoking, and fumaroles. Synonym to vulcanism.
- The solid structure created when lava, gases, and hot particles escape to
the Earth's surface through vents. Volcanoes are usually conical. A
volcano is "active" when it is erupting or has erupted recently.
Volcanoes that have not erupted recently but are considered likely to erupt in
the future are said to be "dormant." A volcano that has not erupted
for a long time and is not expected to erupt in the future is
- Cavity in rock that is lined with long, slender crystals. A vug forms when
air pockets form in cooling magma and allow crystals to form in the hollow