Welcome to the Mineral and precious stone glossary

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Forming "bands" of different colors. See banding. Also refers to wavy bands of veins in surrounding rock.

The presence color zoning lines, or "bands", in some minerals.

Having to do with the base (basal pinicoid).

Type of cleavage exhibited on a horizontal plane of a mineral by way of its base. Minerals with basal cleavage can sometimes be "peeled". Example = minerals of Mica group.

Volcanic rock.

1) The top and the bottom "closing points" of a crystal. A base exists only in minerals that belong to the hexagonal, orthorhombic, tetragonal, and trigonal crystal systems. Also known as basal pinicoid. 2) Matrix or foundation of a crystal. 3) Chemical substance that is either a hydroxide, carbonate, or metal oxide that has the ability to turn litmus paper blue, and the ability to react with acids to form salts. Bases are alkaline and have a bitter taste.

Enormous mass of igneous rock that intruded through a layer of sedimentary rock at great depths.

Complex, scientific test which is conducted to identify a mineral. A mineral is crushed and mixed into a borax flux, and is heated until a glassy bead forms. The bead is then touched by the crushed mineral powder and one of several colors appears on the bead, depending on the metallic elements of the mineral. The colors are different in most cases when heated with an oxidizing and reducing flame, as well as when the bead is hot and cold.

1) Rock mass of one type surrounded by a different type of rock. 2) A deposit of granular rock caused from erosion of solid rock.

The horizontal layers of sedimentary rock still unchanged since the sedimentation process.

Layer of solid rock underneath the soil.

Form of electromagnetic radiation in which the electromagnetic waves are composed of uncombined electrons. See also alpha and gamma waves.

Consisting of hydrocarbons (such as coal) and materials formed from them.

Crystal habit describing flat, elongated, "knife-like" crystals. (i.e. Kyanite)

Complex, scientific test which is conducted to identify a mineral. A mineral fragment is placed in a cavity on a charcoal block, and a horizontal flame is sent towards the fragment on the charcoal using a blowpipe. Depending on the mineral, a different reaction takes place. Certain metals have a characteristic color when flamed, and if the mineral being tested contains such a metal, the charcoal turns that color behind the fragment. Some minerals form a metal bead after being flamed, others give off fumes, and a few volatilize.

he temperature that it takes a substance to start boiling after being in a liquid state.

The link between atoms to form a secure molecule.

Group of minerals that are compounds of one or more metallic elements combined with the borate radical (B2O3). This group forms two sub-groups, the Hydrous borates and the Anhydrous borates. (See "All about borates group")

Industrially used chemical which is an anhydrous form of sodium borate (Na2B4O7) used in the manufacture of glass and ceramics. It is interesting to note that there is a mineral Borax (Na2B4O7 · 10H2O), and it is different than the borax chemical, for it contains water. The mineral Borax is an ore of the chemical borax. See also Kernite.

Aggregate resembling a cluster of grapes. Also known as globular. Rounded agglomerations of botryoidal aggregates are smaller than reniform agglomerations and considerably smaller than mammilary agglomerations.

Synthetic gems created from molten liquids placed in tear shaped molds to crystallize, leaving them with a tear-like form. Mostly applied to synthetic Rubies and Sapphires.

Man-made alloy of copper and zinc. In the olden times, any alloy of copper was known as brass. Most brass of the olden days was an alloy of copper and tin. See also bronze.

Form of tenacity which describes a mineral that gets hammered and results in a fine powder or small crumbs. Minerals that are not brittle are referred as Nonbrittle minerals. Brittle minerals leave a fine powder if scratched, which is the way to test a mineral to see if it is brittle. (See Tenacity in mineral properties for more information.)

"Bronze" is a collective term describing any metallic alloy that range in color from light yellow to orange. Many, if not most alloys described as "bronze" are of copper and tin. See also brass.