Number of Minerals

There are now over 4000 different mineral types recognised by the International Mineralogical Association (IMA) and new mineral types are continually being discovered, verified and added to the list by the Commission on New Minerals and Mineral Names (CNMMN). Many are extremely rare, frequently occur only as small coloured smudges on a piece of parent rock, and are obtainable only as small specimens that have to be viewed using a microscope.

Some collectors aim to collect as many mineral types as possible.

Crystals and Colour

Crystal shape is determined by, and reflects, the rigid geometrical structure of the molecule, called the Unit Cell. The unit cell is the building block of a lattice that determines the crystal shape. All crystals can be allocated to one of only seven crystal systems, each containing a number of classes. The systems and number of classes are cubic (5), tetragonal (7), hexagonal (7), trigonal (5), orthorhombic (3), monoclinic (3) and triclinic (2). Crystal shape is a significant feature in determining a mineral type in the field.
Colour is the least important feature in identifying a mineral but minerals occur in every conceivable colour. For a few examples see the mineral gallery.

Some collectors collect minerals primarily for the aesthetic quality of the crystal shape and colour.

Size

Rapid cooling of a liquid yields small crystals. Large crystals are formed only when cooling is very slow and crystals have time to grow. As crystals grow they are subjected to changes in local geology, pressure and temperature that distort the crystal growth. Large, perfect crystals are therefore extremely rare.
Perfect crystals are mostly found only in micro-specimens.

Micromounters collect small specimens, possibly only match-head size, mounted on a pedestal in a small plastic case measuring no more than 25mm. The specimens are viewed using a microscope.

Micromounters collect small specimens for their rarity and the perfection of crystal shape.

Other Reasons

There are almost as many reasons for collecting minerals as there are collectors.