Product Code Database
Example Keywords: angry birds -mario $11-195
   » » Wiki: Crystal Habit
Tag Wiki 'Crystal Habit'.

Crystal habit

Rank: 100%
Bluestar Bluestar Bluestar Bluestar Blackstar

In , crystal habit is the characteristic external shape of an individual or crystal group. The habit of a crystal is dependent on its crystallographic form and growth conditions, which generally creates irregularities due to limited space in the medium (commonly in rocks).Klein, Cornelis, 2007, Minerals and Rocks: Exercises in Crystal and Mineral Chemistry, Crystallography, X-ray Powder Diffraction, Mineral and Rock Identification, and Ore Mineralogy, Wiley, third edition, Wenk, Hans-Rudolph and Andrei Bulakh, 2004, Minerals: Their Constitution and Origin, Cambridge, first edition,

Recognizing the habit can aid in mineral identification and description, as the crystal habit is an external representation of the internal ordered atomic arrangement. Most natural crystals, however, do not display ideal habits and are commonly malformed. Hence, it is also important to describe the quality of the shape of a mineral specimen:

  • : a crystal that is completely bounded by its characteristic faces, well-formed. Synonymous terms: idiomorphic, automorphic;
  • : a crystal partially bounded by its characteristic faces and partially by irregular surfaces. Synonymous terms: hypidiomorphic, hypautomorphic;
  • Anhedral: a crystal that lacks any of its characteristic faces, completely malformed. Synonymous terms: allotriomorphic, xenomorphic.

Factors influencing habit include: a combination of two or more crystal forms; trace impurities present during growth; and growth conditions (i.e., heat, pressure, space); and specific growth tendencies such as growth striations. Minerals belonging to the same do not necessarily exhibit the same habit. Some habits of a mineral are unique to its variety and locality: For example, while most form elongate barrel-shaped crystals, those found in form stout tabular crystals. Ordinarily, the latter habit is seen only in . Sapphire and ruby are both varieties of the same mineral: .

Some minerals may replace other existing minerals while preserving the original's habit, i.e. . A classic example is tiger's eye , replaced by . While quartz typically forms prismatic (elongate, prism-like) crystals, in tiger's eye the original fibrous habit of crocidolite is preserved.

List of crystal habits
AcicularNeedle-like, slender and/or tapered,

Like embedded , subhedral
BladedBlade-like, slender and flattened, ,
or globularGrape-like, hemispherical masses, , , ,
ColumnarSelenite ()Similar to fibrous: Long, slender prisms often with parallel growth, /selenite
CoxcombAggregated flaky or tabular crystals closely spaced., marcasite
Cubic shape, ,
Dendritic or arborescentTree-like, branching in one or more direction from central point, , native
DodecahedralRhombic dodecahedron, 12-sided
Drusy or encrustationAggregate of minute crystals coating a surface or cavity, ,
EnantiomorphicMirror-image habit (i.e. ) and optical characteristics; right- and left-handed crystals, ,
Equant, stoutLength, width, and breadth roughly equal,
Fibrous (including )Extremely slender prisms, (i.e. )
Filiform or capillaryHair-like or thread-like, extremely finemany
Foliated or micaceous or lamellar (layered)Layered structure, parting into thin sheets,
GranularAggregates of anhedral crystals in matrixbornite,
HemimorphicDoubly terminated crystal with two differently shaped endshemimorphite,
Hexagonal prism (six-sided),
Like cubic, but outer portions of cubes grow faster than inner portions, creating a concavityhalite, , synthetic
MammillaryBreast-like: surface formed by intersecting partial spherical shapes, larger version of botryoidal, also concentric layered aggregatesmalachite,
Massive or compactShapeless, no distinctive external crystal shape, turquoise, ,
Nodular or tuberoseDeposit of roughly spherical form with irregular protuberanceschalcedony
Octahedral, square (eight-sided)diamond, fluorite,
PlatyFlat, tablet-shaped, prominent pinnacoidwulfenite
PlumoseFine, feather-like scalesaurichalcite, ,
PrismaticElongate, prism-like: well-developed crystal faces parallel to the vertical axistourmaline,
Pseudo-hexagonalHexagonal appearance due to cyclic twinningaragonite,
Radiating or radial or divergentRadiating outward from a central point without producing a star (crystals are generally separated and have different lengths)stibnite
Reniform or colloformSimilar to botryoidal/mamillary: intersecting kidney-shaped masses, ,
ReticulatedCrystals forming net-like intergrowthscerussite
Rosette or lenticular (lens shaped crystals)Desert rose ()Platy, radiating rose-like aggregate, (i.e. desert rose)
StalactiticForming as stalactites or stalagmites; cylindrical or cone-shaped, ,
StellateStar-like, radial aggregates radiating from a "star"-like point to produce gross spheres (crystals are not or weakly separated and have similar lengths), , , suns
StriatedNot a habit per se, but a condition of lines that can grow on certain crystal faces on certain minerals, , , ,
Tabular (also stubby or blocky)More elongated than equant, slightly longer than wide, flat tablet-shaped,
Tetrahedral, triangular pyramid (four-sided), ,
Wheat sheafAggregates resembling hand-reaped wheat sheavesstilbite

See also

Page 1 of 1
Page 1 of 1


Pages:  ..   .. 
Items:  .. 


General: Atom Feed Atom Feed  .. 
Help:  ..   .. 
Category:  ..   .. 
Media:  ..   .. 
Posts:  ..   ..   .. 


Page:  .. 
Summary:  .. 
1 Tags
10/10 Page Rank
5 Page Refs
6s Time