Welcome to the Mineral and precious stone glossary

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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.

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 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.

Area in the earth's crust where hot gases or lava escape from.

The escaping of hot gases or lava from the crust of the earth.

The course of creating synthetic gems from molten solutions and letting them form into boules.

Luster describing minerals with reflective properties similar to that of glass.

Disappear as fumes.

Having originated from a volcano.

Rock formed as a direct result of a volcano (i.e. the solidifying of magma).

The volcanic venting effects associated with volcanoes: lava flows, hot springs, smoking, and fumaroles.

A vent in the crust of the earth which spits out molten rock (lava), ash, and gases.

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 area.