The Mineral Identification Key Copper, Michigan, Seaman Museum specimen

Habit is the general appearance a mineral tends to have – whether it is found as blocky crystals, long slender ones, or aggregates of some type, etc.  If the crystals are glassy but cubic in shape you know they aren’t quartz.  If they are rounded like a soccer ball you know they aren’t tourmaline.  And so on…

Distinct crystals may be described as:

Blocky or Equant – Roughly box-like or ball-like, as in pyrite.

Rhodolite garnet, 8 cm across, Brazil

Tabular - Shaped like a pad of paper (thin tabular) or a deck of playing cards (thick tabular).

Barite 4cm across, Bolivia

Prismatic – Elongated with opposite faces parallel to one another, in which case they may be short and stout, or long and thin. Includes minerals such as quartz and tourmaline crystals

Tourmaline (elbaite) 9 cm tall, California
Tourmaline (elbaite) 9 cm tall, California

Bladed - Long thin crystals may be flattened like the blade of a knife.        Actinolite is often bladed.

Stibnite, 5cm across, Romania

Acicular – Needle-like.

Millerite, 1.5cm. long, Wisconsin

Filiform or Capillary – Like hair or thread.

Pyrite filament 0.2 mm long, New Mexico, Dan Behnke photograph


Groups of distinct crystals may be described as:

Druzy - Covering a surface in more-or-less outward pointing clusters of small crystals, such as druzy quartz crystals.

Quartz on chrysocolla, Mexico 2cm across

Divergent or Radiating - Growing outward from a point in sprays or starbursts, such as some hemimorphite exhibits.

Adamite 3.5 cm across,

Reticulated – Interconnected like a lattice or trellis, such as rutile.

Cerussite, Tsumeb, Namibia
 2 cm across

Dendritic or Arborescent - Slender divergent branch- or fern-like clusters, such as some native silver crystals.

Copper, Michigan, 4cm tall


Compact parallel or radiating groups of individual crystals may be described as:

Columnar – Stout parallel clusters with a column-like appearance, such as some forms of the serpentine minerals.

Quartz, 4cm tall, New Mexico

Fibrous – Aggregates of parallel or radiating slender fibers, such as chrysotile.

Silver 2cm across, Czech Republic

Stellate – Long thin crystals radiating outwards in all directions, like a starburst or in a circular pattern, such as astrophyllite.

Natrolite, 10 cm tall, Tasmania, Australia
Natrolite, 10 cm tall, Tasmania, Australia

Spherical or Globular – Compact clusters radiating outwards forming rounded, ball-like, shapes.

Azurite, 10cm across, Arizona
 The next three habits tend to grade into each other

Botryoidal – Globular or ball-like clusters – like a bunch of grapes.

Hematite,  2cm across, Wisconsin

Mammillary – Large rounded masses resembling human breasts.

Quartz variety chalcedony, 4cm across, Nebraska

Reniform – Radiating compact clusters of  crystals ending in rounded, kidney-like, surfaces, such as hematite often exhibits.

Hematite 6 cm across, Wisconsin

A mineral aggregate composed of scales or flakes may be described as:

Foliated – Looking like overlapping flakes or leaves and easily separable into individual leaves or flakes, usually at least somewhat "wavy" in appearance, such as the chlorite minerals.

Talc, 6 cm across, Michigan
Talc, 6 cm across, Michigan

Micaceous – Like foliated, but splits into very thin sheets, like the mica minerals.

Mica schist, Black Hills,
South Dakota, 10cm across

Lamellar – Flat, platy, grains thicker than flakes or leaves, but overlapping like foliated, such as molybdenite.

Molybdenite & 
ferrimolybdenite (yellow),
 Canada 3cm across.

Plumose – Feather-like sprays of fine scales, similar to dendritic but with a much finer structure, such as one form of native silver.

Manganese oxide dendrites, Grant Co. New Mexico 6 cm across
Manganese oxide dendrites, Grant Co. New Mexico 6 cm across

          A mineral composed of grains is simply said to be granular. Granular minerals may be composed of rounded or semi-rounded grains, or of angular grains.


A few other descriptive terms are:

Massive – No crystal structure visible, though the mineral may be crystalline.  Some massive minerals may also be granular.

Forsterite and magnetite,
 Arizona 3cm across

Banded – Showing different bands or layers of  color or texture, as in  some agates or some fluorite.

Goethite, 8 cm tall, Wisconsin

Concentric – In rounded masses showing layers around the mass in shells, working outward from the center, as in some agates.

Quartz var. Lake Superior agate, 5 cm across, Michigan
Quartz var. Lake Superior agate, 5 cm across, Michigan
 The next three habits tend to grade into each other, oolites and pisolites tend to be uncommon

Oolitic – Masses of small round spheres about the size of fish eggs (0.25-2.0mm).

Manganese oxide, 3cm across, Australia

Pisolitic - Roughly pea-size rounded masses.

Manganese oxide, 6cm across, Australia

Concretionary – Masses formed by mineral being deposited around a nucleus, may be spherical or rounded but may also be a wide variety of other shapes.

Top - outside of concretion,
 2cm across, Illinois; 
Bottom - interior of split 
concretion showing fern leaf fossil

Geode – A rock with a hollow, roughly spherical, interior with concentric bands of mineral (usually agate) on the wall and possibly crystals on the interior surface, pointing inwards.

Geode, with quartz and calcite crystals, 8cm across, Mexico

A wide variety of other terms are also used to describe mineral habits.  Usually they refer to loose associations with common objects or concepts and are readily apparent when the term is used in context with the form present in the mineral at hand.

[ Table of Contents ] [ Introduction ] [ Identification Kit ] [ Mineral Properties ] [ Environments & Associations ] [ In Conclusion ] [ The Mineral ID Key ]

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