The Definition of Mineral Habits

01
of 23

Acicular Habit

Needlelike
Gallery of Mineral Habits. Photo (c) Andrew Alden, licensed to About.com (fair use policy)

Habits are the distinctive form that mineral crystals may take in different geologic settings. It refers to the differences in form when they grow in a free space compared to growing in a particular environment, for example. A habit can be a strong clue to a mineral's identity. Here are examples of some of the most useful mineral habits. Note that "habit" also has a meaning for rocks.

Acicular means needlelike. This mineral is actinolite.

02
of 23

Amygdaloidal Habit

Filling almond-shaped holes
Gallery of Mineral Habits. Photo (c) Andrew Alden, licensed to About.com (fair use policy)

Amygdaloidal means almond-shaped, but it refers to the former gas bubbles in lava called amygdules, which are cavities that have become filled with various minerals.

03
of 23

Banded Habit

General term for layered
Gallery of Mineral Habits. Photo (c) Andrew Alden, licensed to About.com (fair use policy)

"Banded" is a broadly layered texture. This rhodochrosite specimen might be called stalactitic, lamellar, geode, or concentric if it were curved differently.

04
of 23

Bladed Habit

Spiky but not needlelike
Gallery of Mineral Habits. Photo (c) 2008 Andrew Alden, licensed to About.com (fair use policy)

Bladed crystals are longer and thinner than tabular crystals but stubbier than acicular crystals. Kyanite is a common example. In rock shops, look for stibnite.

05
of 23

Blocky Habit

Pyrite chunks on quartz
Gallery of Mineral Habits. Photo (c) Andrew Alden, licensed to About.com (fair use policy)

A blocky habit is squarer than equant and shorter than prismatic. This mineral is pyrite on quartz.

06
of 23

Botryoidal Habit

Like grape clusters
Gallery of Mineral Habits. Photo (c) Andrew Alden, licensed to About.com (fair use policy)

In scientific Latin, botryoidal means "like grapes." Carbonate, sulfate and iron oxide minerals tend to have this habit. This specimen is barite.

07
of 23

Cruciform Habit

Crossed twins
Gallery of Mineral Habits. Photo (c) Andrew Alden, licensed to About.com (fair use policy)

The cruciform (cross-shaped) habit is the result of twinning. Staurolite, shown here, is well known for favoring this habit.

08
of 23

Dendritic Habit

A branching form
Gallery of Mineral Habits. Photo (c) Andrew Alden, licensed to About.com (fair use policy)

Dendritic means "like branches." It can refer to flat crystals, like those of manganese oxides, or three-dimensional forms like this specimen of native copper.

09
of 23

Drusy Habit

Crusts of crystals
Gallery of Mineral Habits. Photo (c) Andrew Alden, licensed to About.com (fair use policy)

Druses are a type of opening inside rocks that are lined with projecting crystals. Amethyst, cut from geodes, is commonly sold in rock shops for its pretty drusy habit.

10
of 23

Encrusting Habit

Usually calcite
Gallery of Mineral Habits. Photo (c) Andrew Alden, licensed to About.com (fair use policy)

Calcite, the main component of limestone, commonly dissolves to be deposited elsewhere as a crust. Chips in this specimen show how it coats the underlying rock.

11
of 23

Equant Habit

Round or cubic
Gallery of Mineral Habits. Photo (c) Andrew Alden, licensed to About.com (fair use policy)

Crystals of nearly equal dimensions, like these pyrite crystals, are equant. Those on the left might be called blocky. Those on the right are pyritohedrons.

12
of 23

Fibrous Habit

Like straight hairs
Gallery of Mineral Habits. Photo (c) Andrew Alden, licensed to About.com (fair use policy)

Rutile is typically prismatic, but it can form whiskers as in this rutilated quartz. Curved or bent fibrous minerals are called capillary, or filiform, instead.

13
of 23

Geode Habit

Rocks with druses
Gallery of Mineral Habits. Photo (c) Andrew Alden, licensed to About.com (fair use policy)

Geodes are rocks with open cores, or druses, lined with different minerals. Most geodes contain quartz or, as in this case, calcite with a drusy habit.

14
of 23

Granular Habit

Something like equant
Gallery of Mineral Habits. Photo (c) Andrew Alden, licensed to About.com (fair use policy)

If crystals are not well formed, what might otherwise be called an equant habit is instead called granular. These are spessartine garnet grains in sandy matrix.

15
of 23

Lamellar Habit

Thin-layered gypsum
Gallery of Mineral Habits. Photo (c) Andrew Alden, licensed to About.com (fair use policy)

Lamellae are leaves in scientific Latin, and a lamellar habit is one of thin layers. This gypsum chunk can readily be pried apart into crystal sheets.

16
of 23

Massive Habit

Just solid rock
Gallery of Mineral Habits. Photo (c) Andrew Alden, licensed to About.com (fair use policy)

The quartz in this gneiss boulder has a massive habit, with no individual grains or crystals visible. Caution: rocks may also be described as having a massive habit, too. If you can, use a more appropriate term like equant, granular or blocky to describe them.

17
of 23

Micaceous Habit

Much thinner than lamellae
Gallery of Mineral Habits. Photo (c) Andrew Alden, licensed to About.com (fair use policy)

Minerals that split into extremely thin sheets have a micaceous habit. Mica is the prime example. This chrysotile specimen from an asbestos mine also has thin sheets.

18
of 23

Platy Habit

This gypsum sheet fits the bill
Gallery of Mineral Habits. Photo (c) Andrew Alden, licensed to About.com (fair use policy)

A platy habit might be better described as lamellar or tabular in some instances, but this thin sheet of gypsum can be called nothing else.

19
of 23

Prismatic Habit

Tourmaline is the textbook example
Gallery of Mineral Habits. Photo (c) Andrew Alden, licensed to About.com (fair use policy)

Prism-shaped minerals are common in granites. Tourmaline's nine-faced prisms are distinctive and diagnostic. Very long prisms are called acicular or fibrous.

20
of 23

Radiating Habit

Shown by a pyrite dollar
Gallery of Mineral Habits. Photo (c) Andrew Alden, licensed to About.com (fair use policy)

This "pyrite dollar" grew from a central point, squeezed flat between shale layers. The radiating habit can have crystals of any form, from blocky to fibrous.

21
of 23

Reniform Habit

Kidney-shaped
Gallery of Mineral Habits. Photo (c) Andrew Alden, licensed to About.com (fair use policy)

Reniform refers to being kidney-shaped. Hematite displays reniform habit well. The fracture shows that each round mass consists of radiating small crystals.

22
of 23

Rhombohedral Habit

A skew cube
Gallery of Mineral Habits. Photo (c) Andrew Alden, licensed to About.com (fair use policy)

Rhombohedrons are bent cubes in which no corner is straight; that is, each face of this calcite grain is a rhombus, and there are no right angles.

23
of 23

Rosette Habit

A barite rose
Gallery of Mineral Habits. Photo (c) Andrew Alden, licensed to About.com (fair use policy)

Rosettes are groups of tabular or bladed crystals arranged around a central point. These barite rosettes are composed of tabular crystals.

Format
mla apa chicago
Your Citation
Alden, Andrew. "The Definition of Mineral Habits." ThoughtCo, Feb. 28, 2017, thoughtco.com/all-about-mineral-habits-4122987. Alden, Andrew. (2017, February 28). The Definition of Mineral Habits. Retrieved from https://www.thoughtco.com/all-about-mineral-habits-4122987 Alden, Andrew. "The Definition of Mineral Habits." ThoughtCo. https://www.thoughtco.com/all-about-mineral-habits-4122987 (accessed September 20, 2017).