In mineralogy, shape and size give rise to descriptive terms applied to the typical appearance, or habit of crystals. Mineralogy is an earth science that involves the chemistry, crystal structure, and physical (including optical) properties of minerals. ...
It has been suggested that crystallization processes be merged into this article or section. ...
Pyrite sun (or dollar) in laminated shale matrix. Between tightly spaced layers of shale, the aggregate was forced to grow in a laterally compressed, radiating manner. Under normal conditions, pyrite would form cubes or pyritohedrons.
The many terms used by mineralogists to describe crystal habits are useful in communicating what specimens of a particular mineral often look like. Recognising numerous habits helps a mineralogist to identify a large number of minerals. Some habits are distinctive of certain minerals, although most minerals exhibit many differing habits which are influenced by certain factors. Crystal habit may mislead the inexperienced as a mineral's crystal system can be hidden or disguised. Pyrite sun (or dollar) in laminated shale matrix. ...
Pyrite sun (or dollar) in laminated shale matrix. ...
Rose des Sables (Sand Rose), formed of gypsum crystals In mineralogy and crystallography, a crystal structure is a unique arrangement of atoms in a crystal. ...
Factors influencing a crystal's habit include: a combination of two or more forms; trace impurities present during growth; crystal twinning and growth conditions (i.e., heat, pressure, space). Minerals belonging to the same crystal system do not necessarily exhibit the same habit. Some habits of a mineral are unique to its variety and locality: For example, while most sapphires form elongate barrel-shaped crystals, those found in Montana form stout tabular crystals. Ordinarily, the latter habit is seen only in ruby. Sapphire and ruby are both varieties of the same mineral; corundum. It has been suggested that twin boundary be merged into this article or section. ...
Sapphire (from Hebrew: ×¡×¤Ö¼××¨ Sapir) is the single-crystal form of aluminium oxide (Al2O3), a mineral known as corundum. ...
Official language(s) English Capital Helena Largest city Billings Area Ranked 4th - Total 147,165 sq. ...
Ruby is a red gemstone, a variety of the mineral corundum (aluminium oxide) in which the color is caused mainly by chromium. ...
Corundum is the crystalline form of aluminium oxide and one of the rock-forming minerals. ...
Some minerals may replace other existing minerals while preserving the original's habit: this process is called pseudomorphous replacement. A classic example is tiger's eye quartz, crocidolite asbestos replaced by silica. While quartz typically forms euhedral (well-formed), prismatic (elongate, prism-like) crystals, in tiger's eye the original fibrous habit of crocidolite is preserved. Polished tigers eye gemstone Tigers eye (also Tigers eye, Tiger eye) is a chatoyant gemstone that is usually yellow- to red-brown, with a silky luster. ...
Quartz is amongst one of the most common minerals in the Earths continental crust. ...
Amphibole (Hornblende) Amphibole defines an important group of dark-colored rock-forming inosilicate minerals composed of double chain SiO4 tetrahedra linked at the vertices and generally containing ions of iron and/ or magnesium in their structures. ...
Fibrous asbestos on muscovite Asbestos Asbestos Asbestos (a misapplication of Latin: asbestos quicklime from Greek á¼ÏÎ²ÎµÏÏÎ¿Ï: a-, not; sbestos, extinguishable) describes any of a group of fibrous metamorphic minerals of the hydrous magnesium silicate variety. ...
The chemical compound silicon dioxide, also known as silica, is the oxide of silicon, chemical formula SiO2. ...
List of crystal habits
|Habit: ||Description: ||Example: |
|Acicular ||Needle-like, slender and/or tapered ||Rutile in quartz |
|Amygdaloidal ||Almond-shaped ||Heulandite |
|Anhedral ||Poorly formed, distorted ||Olivine |
|Bladed ||Blade-like, slender and flattened ||Kyanite |
|Botryoidal or globular ||Grape-like, hemispherical masses ||Smithsonite |
|Columnar ||Similar to fibrous: Long, slender prisms often with parallel growth ||Calcite |
|Coxcomb ||Aggregated flaky or tabular crystals closely spaced. ||Barite |
|Dendritic or arborescent ||Tree-like, branching in one or more direction from central point ||Magnesite in opal |
|Dodecahedral ||Dodecahedron, 12-sided ||Garnet |
|Drusy or encrustation ||Aggregate of minute crystals coating a surface ||Uvarovite |
|Enantiomorphic ||Mirror-image habit and optical characteristics; right- and left-handed crystals ||Quartz |
|Equant, stout, stubby or blocky ||Squashed, pinnacoids dominant over prisms ||Zircon |
|Euhedral ||Well-formed, undistorted ||Spinel |
|Fibrous or columnar ||Extremely slender prisms ||Tremolite |
|Filiform or capillary ||Hair-like or thread-like, extremely fine ||Natrolite |
|Foliated or micaceous ||Layered structure, parting into thin sheets ||Mica |
|Granular ||Aggregates of anhedral crystals in matrix ||Scheelite |
|Hemimorphic ||Doubly terminated crystal with two differently shaped ends. ||Hemimorphite |
|Mamillary ||Breast-like: intersecting large rounded contours ||Malachite |
|Massive or compact ||Shapeless, no distinctive external crystal shape ||Serpentine |
|Nodular or tuberose ||Deposit of roughly spherical form with irregular protuberances ||Geodes |
|Octahedral ||Octahedron, eight-sided (two pyramids base to base) ||Diamond |
|Plumose ||Fine, feather-like scales ||Mottramite |
|Prismatic ||Elongate, prism-like: all crystal faces parallel to c-axis ||Tourmaline |
|Pseudo-hexagonal ||Ostensibly hexagonal due to cyclic twinning ||Aragonite |
|Pseudomorphous ||Occurring in the shape of another mineral through pseudomorphous replacement ||Tiger's eye |
|Radiating or divergent ||Radiating outward from a central point ||Pyrite suns |
|Reniform or colloform ||Similar to mamillary: intersecting kidney-shaped masses ||Hematite |
|Reticulated ||Acicular crystals forming net-like intergrowths ||Cerussite |
|Rosette ||Platy, radiating rose-like aggregate ||Gypsum |
|Sphenoid ||Wedge-shaped ||Sphene |
|Stalactitic ||Forming as stalactites or stalagmites; cylindrical or cone-shaped ||Rhodochrosite |
|Stellate ||Star-like, radiating ||Pyrophyllite |
|Striated/striations ||Surface growth lines parallel or perpendicular to c-axis ||Chrysoberyl |
|Tabular or lamellar ||Flat, tablet-shaped, prominent pinnacoid ||Ruby |
|Wheat sheaf ||Aggregates resembling hand-reaped wheat sheaves ||Zeolites |