Articles and Information on Crystals and Healing
AGATE & JASPER PHYSICAL PATTERNS
Sagenite is a vein or nodular crystal with needle like inclusions occurring loosely dispersed or collectively in sprays or fan shapes.
Sagenite has a clear chalcedony background where the needles are uninterrupted and appear to be floating freely. Sagenite needles are composed of a variety of minerals, including rutile, manganese, chlorite, actinolite or goethite, and are often pseudomorphic replacements of other minerals such as barite or aragonite.
Snowflake is a vein or nodular crystal that has little floating white flecks or flakes in clear chalcedony that looks like snowflakes. Snowflakes tend to occur in banded agates and jaspers, but can appear in almost any of the other types. In some dendritic agates and jaspers, the snowflakes are coloured black and brown.
Spherulites are small, rounded bodies that commonly occur in Agate and Jasper rocks. They are often visible in stones as globules about the size of millet seed or rice grain, with a duller lustre than the surrounding glassy base of the rock, and when they are examined with a lens they prove to have a radiate fibrous structure.
A spiderweb pattern is a criss-cross or woven type of pattern overlaying a solid colour background. spiderweb agates and jaspers can occur in colours of green, red black cream and brown. Some spider web patterns are small and delicate while others are large and flashy these ones are also called Picasso stones.
Tube Pattern is a vein or nodular agate with internal pseudomorphic replacement of crystals or needles that create a stalactite or tube like formations within the stone. It looks like a worm has crawled around inside the rock. When the agate is cut parallel to the pattern it shows long finger like tubes, and when cut across the tube an eye pattern is shown.
A waterline Agate is a nodular or vein agate that exhibits straight rows or coloured lines, usually white on a clear chalcedony background. Waterline agate can occur with other agate patterns, such as banded, dendritic, or moss types. Waterline agate is also known as Onyx Agate or Uruguay banding.
VISUAL EFFECTS OF CRYSTALS
A botryoidal texture or mineral habit is one in which the mineral has a globular external form resembling a bunch of grapes as derived from the Greek. This is a common form for many minerals particularly hematite where it is the classically recognised shape.
It is also a common form of goethite, smithsonite, fluorite and malachite. This includes chrysocolla.
Chatoyancy or Chatoyance or Cat's eye effect, is an optical reflectance effect seen in certain gemstones.
Coined from the French "œil de chat," meaning "cat's eye," chatoyancy arises either from the fibrous structure of a material, as in Jaspers, or from fibrous inclusions or cavities within the stone, as in cat's eye chrysoberyl.
The effect can be likened to the sheen off a spool of silk: The luminous streak of reflected light is always perpendicular to the direction of the fibres. For a gemstone to show this effect best it must be cut en cabochon, with the fibres or fibrous structures parallel to the base of the finished stone. Faceted stones are less likely to show the effect well.
A druzy crystal is a configuration of many tiny sparkling crystals on the surface of a bulky crystalline body. This effect usually grows over another matrix
A druzy crystal can grow over agate or any other colored matrix. Building this crystalline effect is not only a feature of Quartz. Minerals like calcite, malachite, dolomite, and garnet are also found as druzy stones.
In their natural form the color of druzy stones can vary from almost transparent, to translucent and opaque.
The fire effect is achieved through iridescent spheroids of limonite (iron) being laid down in a clear crystal; generally agate or opal; which then creates its beautiful rainbow of colors ranging from brownish-red and orange to blue and
This iridescent coloring is created by the Schiller effect, caused by alternating silica or opal and iron layers which diffract and pass light back and forth to create the “fire”.
Crystals, may have a distinctive fluorescence or may fluoresce differently under short-wave ultraviolet, long-wave ultraviolet, visible light, or X-rays.
Many types of calcite and amber will fluoresce under shortwave UV, longwave UV and visible light.
Rubies, emeralds, and diamonds exhibit red fluorescence under long-wave UV, blue and sometimes green light; diamonds also emit light under X-ray radiation.
Fluorescence in crystals is caused by a wide range of activators; for example,
manganese, is responsible for the red or orange fluorescence of calcite, the green fluorescence of willemite, the yellow fluorescence of esperite, and the orange fluorescence of wollastonite and clinohedrite.
An Iris effect occurs in banded translucent crystals. At first glance an iris crystal looks like a normal banded agate or similar crystal, but when it is backlit by a light source the tight chalcedony bands within the stone act as a diffraction grating, separating white light into its constituent spectral colours which change as the stone is revolved and rotated.
Opalescence is also called adularescence and milkiness. This effect is caused by a scattering of light within the crystal by thin microcrystalline layers. It can be a white haziness or soft colorations. Opal, moonstone (adularia), agate and milky quartz are the gemstones best known for this special effect.
When banded and fortification agates have very tight banding a phenomena occurs called parallax, this is a visual effect that resembles a shadowy movement within the stone's bands when is is slowly rotated in the light.
Schiller is a play of colour in a crystal, in which the interior of a stone displays flickers of color as it is moved in the light. Opal is especially valued for this trait. There is no actual object inside the stone. This special effect arises from light interference within the microstructure of the mineral. Other examples of crystals that display a schiller effect are Moonstone, Labradorite and Sunstone.
Geodes are formed by Chalcedony that is deposited in layers in cavities leaving hollow centres. The hollow centres are then lined with other crystals such as amethyst, clear quartz, garnet, and calcite. They are primarily cut in half and polished as display specimens although some of the smaller geode slices are used in jewellery.
Massive is the common name used for an amorphous structure that is thick and dense often in large solid chunks or seams. The most common massive crystal structures are the quartz and limestone. The photo shows massive selenite beams in a mine in Mexico and yes there are people in the image.
A nodule has a warty or knobby surface and exists as a discrete mass within the host strata. Nodules are closely related to concretions and sometimes these terms are used interchangeably. Minerals that typically form nodules include calcite, chert, apatite, anhydrite, and pyrite.
A polyhedral is a sharply geometric or angular shaped nodule generally growing on a base crystal or matrix. In general each side of the polyhedral shape are equal.
The main 3D shapes are tetrahedron (pyramid), hexahedron (cube), octahedron (8 sides), dodecahedron (12 sides), and icosahedron (20 sides) are the five regular polyhedrons.
Pseudomorphs are formed when minerals, usually in the form of chalcedony replace another mineral or organic substance and the shape is retained of the original object, but its chemical composition has been permanently altered. The item replaced maybe animal such as dinosaur bones or marine coral; plant matter such as fossilised wood or fossilised ferns; or other minerals, such as barite or aragonite crystals that are replaced and filled by chalcedony. Other crystals such as calcite, pyrite, azurite, malachite, and goethite may also form as replacement materials.
A thunder egg is a nodule-like rock, it appears to be a filled geode. Thunder eggs are rough spheres. They usually contain centres of chalcedony either uniquely or in combination with agate, jasper or opal. Also frequently encountered are quartz and gypsum crystals, as well as various other mineral growths and inclusions. Thunder eggs usually look like ordinary rocks on the outside, but slicing them in half and polishing them may reveal intricate patterns and colours.