About Us
Site Map
Animal Stones
Shaped ones
for a Pendant
Bookmarks &
Books & CD's
Chip Bead
Chip Bead
Tampa Bay Coral
Heart Beads
Horse Hair
Key Chains
Chip Beads
Ocean Jasper
A to L
M to Z
Pendant &
Earring Sets
Pouches &
Quartz Lemurian
Shiva Lingam's
Smudge &
A to C
D to N
O to Z

Glossary of Mineralogical Terms

Banding - The presence of color zoning lines, or "bands" or lines of different colors, in some minerals, such as Agate, Malachite and Onyx.
Basal Cleavage - Type of cleavage exhibited on a horizontal plane of a mineral by way of its base. Minerals with basal cleavage can sometimes be peeled. A good example is minerals of the Mica group.
Botryoidal - A mineral surface that resembles a cluster of grapes, this describes certain minerals such as Chalcedony, Hematite and Malachite.
Cabochan - A style of cutting in which the top of the gemstone forms a curved convex surface. The base may be convex, concave or flat.
Carat - A weight measurement used in reference to gemstones in regard to their evaluation. A carat is .2 grams (or 200 milligrams), and this weight is used worldwide, even in the U.S. where the metric system isn't used. A point is the weight used only in reference to very small, precious gemstones and represents 1/100th of a carat. The abbreviation for carat is ct. and for point is pt. 
The term carat in regard to gemstones should not be confused with the term carat in regard to gold. By gold, it refers to the content and quality of the gold in the ornament. Because of the confusion, the term carat in regard to gold has been changed to karat.  See Karat.
Cat's Eye - A mineral or gemstone with dense inclusions of tiny, parallel, slender, fibers that may cause it to exhibit chatoyancy.  The most notable Cat's eye is Chrysoberyl Cat's Eye, which is known simply as Cat's Eye. Other Cat's eye minerals are termed by their respective names, such as a Cat's eye Quartz which is known as "Quartz Cat's Eye".
Cavity - Hollow area in rock that develops because of some form of stress. Many cavities are lined with crystals.  See also Vug.
Chatoyancy - Phenomenon of certain Cat's eye minerals which causes them to exhibit a concentrated narrow band of reflected light across the center of the mineral. Chatoyancy is almost exclusively exhibited on polished cabochons or polished stones.
Cluster - Dense agglomeration or group of crystals.
Conchoidal Fracture - Mineral fracture in which the indentation resembles a shell.
Cubic - Having the form of a cube, as a cubic crystal.
Dendrite - A branching figure resembling a tree produced on or in a mineral or stone by an oxide of Manganese or other foreign mineral (as in Moss Agate) or the mineral or stone so marked.
Dendritic - Branch and moss like shapes or markings. For example, some crystallized native gold.
Distorted crystal - A crystal whose faces have developed unequally, some faces being larger than others. Some distorted crystal forms are drawn out or shortened, but the angle between the faces remains the same.
Druse - A cavity in a rock or vein with walls encrusted with small projecting crystals.
Druzy - Type of aggregate describing a dense coating of small sharp crystals over a surface. A well known example is small pointed Quartz crystals densely lining a geode.
Facet - A desired surface displayed in a gem. It may grow naturally but is usually hand cut.  This definition also includes the meaning of a specific cut for gems.
Floater Crystal -   A crystal that developed without being attached to a host rock, such as being grown artificially in a lab or having been grown naturally in clay or water. All sides of floater crystals are usually fully intact being that they don't have an attachment point.  A floater crystal may also refer to a crystal that lacks any attached matrix.
Fluorescence - The emission of visible light by a substance exposed to ultraviolet (UV) light. Some materials, when exposed to invisible UV radiation, emit visible light and seem to "glow-in-the-dark."
Fossil - Animal or plant remains of a previous age embedded and preserved in rock.
Fracture - A. The way in which a mineral breaks, other than its cleavage.  B. A crack, joint or break in rocks.
Glass - Natural  - Type of igneous rocks that forms from rapid cooling of molten rock occurs. Natural glasses, such as Obsidian, are amorphous, without a crystal structure and are usually with a rounded shape. They often contain visible conchoidal fractures.
Geode - A hollow nodule or concretion with the cavity which is commonly lined with crystals.
Inclusion - Minerals or other foreign materials locked inside a crystal as it is forming.
Incrustation Pseudomorph aka Encrustation or Epimorph -  A pseudomorph occurring when a mineral forms a coating over another mineral and the coated mineral dissolves. This leaves a hollow cast of the original mineral that was dissolved.
Infiltration Pseudomorph - A pseudomorph occurring when some atoms of a mineral are replaced by other atoms which cause it form a scientifically different mineral.
Intergrowth - An interlocking of two or more minerals that resulted from their simultaneous crystallization.
Iridescent - Rainbow-like colors on the interior or surface of a mineral.
Iridescence - Light effect causing a mineral to display a play of colors on an apparently monocolored surface. Iridescence is often the result of pearly luster, seen around an area where pressure occurred (displaying a similar image to that of fresh oil rising to the surface of a road at the beginning of a rain).  Iridescence is also the result of mild tarnishing of a few metallic lustered minerals, such as Chalcopyrite and Rainbow Hematite.
Irradiation - The act of being exposed to radiation. This has an effect on several gemstones by altering their natural color.
Karat - Unit of measurement describing the content of Gold in an ornament. The karat unit measures the percentage of Gold in metallic objects made of Gold (mainly jewelry). Since pure Gold is very flexible and bends very easily, it is mixed with tougher metals when made into ornaments to form a tougher, although impurer, Gold. The karat measurement determines the percentage of gold on a 1 to 24 scale, with 24 karats being pure gold. That means that 14 karat gold is only 14/24 (or 58.33%) Gold. Gold with too high of a karat measurement is undesirable for jewelry because it is soft and bendable and gold with a low karat measurement is undesirable because of its lesser value.
The term karat is often confused with the term carat, which is the weight measurement for gemstones.  The abbreviation of karat is k. or kt.
Lapidary - A craftsman who cuts and polishes precious and semi precious stones.
Luminescence - General term describing the capability of a mineral with a habit of giving off light when put under certain conditions. Three examples of luminescence are fluorescence, triboluminescence, and thermoluminescence.
Luster - The way a mineral reflects light or shines. It is one of the means for distinguishing minerals.
Magnetism - The phenomenon of certain metals to attract other metals.
Metallic - 1. Having the attributes of a metal. or 2. May also be used to describe a mineral with a metallic luster although it is not a true metal.
Meteor - Meteorites - Mass of extraterrestrial rock that gets pulled in to the Earth's gravitational pull. Some meteors can be seen streaking across the atmosphere before they burn up or land on earth. These are known as "shooting stars". Meteors that don't burn up and land on the earth are known as meteorites.
Mica - Individual member of the mica group. May also refer to any mineral similar to the true micas that have perfect basal cleavage and can be "peeled". 
Mica group - Group of related minerals that contain aluminum silicate. The percentage of their component elements may vary, which often causes the Mica's not to be recognized as a series. The Micas are soft and have perfect basal cleavage, which allows individual members to be "peeled". 
Micromount see also Thumbnail - Describes a mineral specimen from a collection that is about 1/2 an inch or smaller in size (approximately 13 mm), and is usually stored in a small, clear plastic box mounted on a thin stand. There are collectors that specialize in micromount minerals.
Mohs' Hardness - The Mohs hardness scale is a scale of relative hardnesses based on ten common standard minerals. A mineral with a higher Mohs number can scratch a mineral with a lower number.

1 Talc
2 Gypsum
3 Calcite
4 Fluorite
5 Apatite
6 Orthoclase
7 Quartz
8 Topaz
9 Corundum
10 Diamond

By sheer coincidence, the scale turns out to be logrithmic, with each mineral going up the scale turning out to be twice as hard as the previous on an absolute scale.  Such as Fluorite is twice as hard as Calcite, and Apatite is twice as hard as Fluorite. The exception is Diamond, which is considerable more than twice as hard as Corundum, it is something on the order of eight times as hard.

Mother of Pearl - The iridescent inside of a mollusk shell, not to be confused with Pearl.
Multicolored - Exhibiting two or more colors on a single specimen. An excellent example is multicolored Tourmaline.
Opalescence - Color effect seen in Opal which causes it to exhibit a glimmer of different colors when rotated or seen in different angles.
Opalization - The habit of Opal replacing other minerals as well as organic material such as in wood and shells.
Opaque - Not able to transmit light, which in effect disables an opaque mineral from letting an object not be able to be be seen through.
Oxidize - 1. Property exhibited in certain minerals that cause them to tarnish, or discolor upon contact with air such as Copper.   2. Also used to describe the chemical alteration of one mineral into another mineral through contact with air.
Paramorph - A pseudomorph involving two minerals with an identical composition but different crystal structures. The original mineral forms, but conditions then cause it to be unstable, so it transforms into the other mineral with the same chemical structure while retaining the original crystal shape.  An example of this is Aragonite (CaCO3 - Crystallizes in the orthorhombic system) that becomes unstable and transforms into Calcite (CaCO3 - Crystallizes in the trigonal system), but retains the original orthorhombic shape.
Penetration - The formation of a crystal penetrating through a rock or another crystal.
Petrification - Process in which organic substances, such as wood and shells, are replaced by silica, such as Quartz and Opal.
Petrify -  To become stone. Organic substances such as shells, stones and wood embedded in sediments become converted into stone by the gradual replacement of their tissues, particle by particle, with corresponding amounts of infiltrated mineral matter.
Petrified - Having been replaced by silica after once being organic.
Phantom - An interesting phenomenon exhibited when a crystal grows, then a new growth grows over the old crystal in the same direction, leaving a ghost of the previous growth within the crystal. Additional growth may be present, leading to the possibility of more than one phantom in a crystal.
Pseudomorph    This term litterally means "false form," or "false shape." In mineralogy it is used to describe a crystal of one mineral which has replaced another without changing the crystal structure to that of the new mineral. The constituents of the original mineral are chemically replaced by those of the second without disturbing the structure or symmetry of the original crystal. Example: In a Talc pseudomorph after Actinolite the original acicular aggregate habit of the Actinolite is still seen even though the Actinolite has been entirely replaced by the mineral talc. The term is usually abbreviated as either "pseudo." or "ps." Also see paramorph. (Not to be confused with the use of "pseudo-" as a crystallographic prefix, which see also.)
Scepter - A mineral habit in which growth has been renewed on the tip of a prismatic crystal, creating a second crystal of the same mineral encasing the tip of the original crystal. The resulting double crystal looks somewhat like a royal scepter. Most commonly seen in Quartz crystals.
Sheen - The way a mineral reflects light can be affected by characteristics just below the mineral's surface: for example, the pearly sheen caused by partly-developed cleavage(s) parallel to the surface; the silky sheen from a fibrous growth structure or parallel hair-like inclusions.
Tabular - Crystal habit with the appearance of a paper tablet.
Thermoluminescence - Phenomenon exhibited in certain minerals that they give off light, like a glow, when heated. Can only be observed in a dark area.
Thumbnail - Describes a mineral specimen from a collection that about about 1 inch (2.5 cm.) in size, usually stored in a small, clear plastic box. Many collectors specialize in thumbnail minerals.
Transparent  - Describing an object that is able to transmit light through it, and if placed in front of another object, that object can be seen through it.  Minerals that can be seen through are transparent.
Triboluminescence - Property exhibited in certain minerals which causes them to give off orange or yellow "flashes" when sawed or struck by a hard substance.
Twin - An intergrowth of two or more single crystals of the same substance.
Vein - A zone or belt of mineralized rock lying within boundaries clearly separating it from neighboring rock. It includes all deposits of mineral matter found through a mineralized zone or belt coming from the same source, impressed by the same forms, and appearing to have been created by the same method.
Ventifacts - Rocks that have been abraded, pitted, etched, grooved or polished by wind driven sand or ice crystals.
Vug - A cavity in rock that is lined with crystals. Vugs often form when air pockets form in cooling magma and allow crystals to form in the hollow area, but may also be present in sedimentary or metamorphic environments.

Back Next

Disclaimer: The information regarding the metaphysical, other properties and purposes of these minerals are provided for entertainment purposes only. It is not intended for diagnosing illness, prescription or advice and should not replace proper medical attention. Please consult your Doctor or other health care practitioner regarding health issues. Dragon's Crystal Reverie or Alyce Love assume no liability for any use or misuse of this information.

If you have any questions, comments or wish to purchase with check or money order
please email us at, thanks!

Web Site designed by Dragon's Reverie™