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Vanadinite is a source of vanadium and a minor ore of lead (consisting of lead vanadate with a small proportion of lead chloride). It is found occurring in yellowish, and ruby-red hexagonal crystals in the oxidized portion of lead veins associated with other lead minerals. Vanadium is used as a steel- hardening metal. It has a relative hardness of 3.
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Variolite is a kind of diorite or diabase containing imbedded whitish spherules, which give the rock a spotted appearance.
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Variscite, named after Variscia in Germany, is an apple-green or pink coloured secondary mineral occurring in reniform masses. In its pure form it is a hydrated phosphate of aluminium. Variscite was confirmed as a distinct species of mineral in 1837.
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Vauquelinite, named after the French chemist Vauquelin, is a chromate of copper and lead, of various shades of green.
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In geology a vein is a narrow mass of rock intersecting other rocks, and filling inclined or vertical fissures not corresponding with the stratification. Such mineral ores have usually been deposited from solutions, and may be metallic or non-metallic; as a general rule, the two kinds are found in veins together. The non-valuable mineral deposit in a vein is known as the gangue. Veins are sources of many of the valuable metals, e.g. gold and silver, and vary in size from the almost invisible to several hundred feet in thickness.
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Venus' Hair is a popular name for a variety of quartz penetrated by acicular crystals of rutile.
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Vermiculite is a group of minerals having, a micaceous structure. They are hydrous silicates, derived generally from the alteration of some kind of mica. They are so called because the scales, when heated, open out into worm- like forms. Processed vermiculite is used as an insulating material in building.
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Vesicle refers to a small cavity in a volcanic rock.
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Vesuvianite (also known as idocrase) is a mineral usually found in crystalline limestones occurring in tetragonal crystals, and also massive, of a brown to green colour, rarely sulphur yellow and blue, and is formed as a result of contact metamorphism. It is a silicate of alumina and lime with some iron magnesia and has the formulae Ca10(Mg,Fe) 2Al4(SiO4)5(SiO7)2(OH)4 and a relative hardness of 7. Vesuvianite was confirmed as a distinct species of mineral in 1795 and named vesuvianite after Mount Vesuvius in Italy where typical specimens are found.
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Vicinal planes are subordinate planes on a crystal, which are very near to the fundamental planes in angles, and sometimes take their place. They have in general very complex symbols.
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Viridite is a greenish chloritic mineral common in certain igneous rocks, such as diabase, as a result of alternation.
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Vitreous refers to a lustre like that of glass. Quartz is an example.
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Vivianite, named after the English mineralogist J G Vivian who discovered the mineral in Cornwall, England, is a rare mineral of secondary origin, associated with pyrite in copper and tin veins. It forms as a weathering product from primary iron- manganese phosphates in pegmatites, and is a hydrous phosphate of iron of a blue to green colour, growing darker on exposure to the air. It occurs in monoclinic crystals, also fibrous, massive, and earthy. It is also found in beds of clay and has a relative hardness of 1.5 to 2. Vivianite was confirmed as a distinct species of mineral in 1817.
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Volborthite, named after its discoverer, Volborth, Is a mineral occurring in small six-sided tabular crystals of a green or yellow colour. It is a hydrous vanadate of copper and lime.
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A volcanic neck is a column of igneous rock formed by the congregation of lava in the conduit of a volcano and later exposed by the removal of surrounding rocks.
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Voltzite (voltzine), named in honour of the French engineer Voltz, is an oxysulphide of lead occurring in implanted spherical globules of a yellowish or brownish colour.
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Vulpinite, named after Vulpino, in Italy, is a scaly granular variety of anhydrite of a greyish white colour, used for ornamental purposes.
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Abbreviations
Rocks & Minerals
