Single Mineral Habit - Room to grow
Minerals occur in different shapes and sizes, giving rise to descriptive terms applied to their typical external appearance, or habit. Some habits are distinctive of certain minerals and reflect their internal crystal structure and symmetry. Minerals with the same crystal symmetry may crystallize in different habits depending on the temperature, pressure and space conditions during their formation. Only if minerals are allowed to grow in a free space without interference from other minerals will they form crystals in their characteristic habit.
Pyrite FeS2
Equant Habit
Pyrite crystals with equal width, height and length in a cubic, octahedral and dodecahedral shape
Cube: 3 cm
Pyrite Penetration Twin
Navajun, Spain
Size: 4.2x3.7x3.3cm, 2.6x2.4x2.3cm
Two crystals of the same mineral crystallize together in such a way that they are joined at a common symmetry or crystallographic plane forming a twinned crystal. When two parts of the twinned crystals grow into each other, they are called penetration twin.
Galena PbS
Equant, blocky Habit
Assemblage of galena crystals in their cubic shape
Size: 20 cm
Flourite CaF2
Equant Habit
Flourite crystals with equal width, height and length in a cubic and octahedral shape
Top: 8cm
Bottom: 3cm each
Quartz SiO2
Prismatic Habit
One of the most common of crystal Habits being “pencil-like", elongated along one axis
Size: 10 cm
Carborundum SiC
Tabular Habit
Broad, flat or book-like crystals
Size: 15 cm
Calcite - Iceland spar CaCO3
Rhombohedral Habit
Bent cubes in which each face of the crystal is a rhombus with no right angles
Size: 5 cm each