This term covers a group of minerals that can grow in association with calcites and quartz - and with each other - often combined in a single specimen. This can make them hard to identify as individual minerals, although their colour, growth habit and structure (e.g. acicular or needle-like prismatic crystals, flattened platy, fanned or tabular crystals) can aid identification. The most commonly identified zeolites are:
HEULANDITE:
Often ‘blocky’ diamond-shaped, trapezoidal or ‘coffin- shaped’ crystals, sometimes producing a crust of curved pearly faces – commonly coloured white, pink or peach.
NATROLITE:
Often needle-like crystal, commonly clear or coloured white or pale peach. May also form square prisms.
STILBITE:
Typically thin tabular crystals that grow in flattened elongated sheaths along an axis, often double ended like a bow-tie. Twinned, cruciform and penetration clusters are also common. Usually coloured pearly white, but also yellow, pink, peach or orange.
Zeolites may also be found in combination with other crystals, including:
APOPHYLLITE:
Crystals are usually clear, white or pale green; and may be cubic or have pyramidal terminations.
SCOLECITE:
Crystals are usually clear or white, long and delicately needle-like, often with a common core, so that the clusters can appear almost spherical.
CAVANSITE:
Crystals are platy or needle-like, bright ‘neon’ blue and small, usually forming in tiny spiky spherical clusters.
Like all such groupings the specimen concerned will combine the attributes of each of the individual minerals.
Inner Light Crystals
