The AUTUMN COLLECTION - Fall colors from Australia !

The golden tones of Autumn make their appearance in several gemstones that are used for jewelry. In this case Mookaite, yellow Calcite and yellow Jade are selected for this purpose.

Mookaite and yellow Jade chips make a double-scallop on either side of a Mookaite tear drop pendant.
Calcite ovals, round beads and silver plate beads add demension to the sides of this 21 inch necklace.

The necklace is closed with a sliver plated Toggle clasp and a 2 inch extender.
Silver plate French Hook hoop earrings have a drop of 2 inches.

Mookaite --- see the previous Blog on September 1st for the explanation about Mookaite.

Calcite, which gets its name from "chalix" the Greek word for lime, is a most amazing and yet, one of the most common minerals on the face of the Earth, comprising about 4% by weight of the Earth's crust and is formed in many different geological environments. Calcite can form rocks of considerable mass and constitutes a significant part of all three major rock classification types. Some of these rock types are composed of better than 99% calcite. Why would a collector be interested in such a common mineral? Because of its extraordinary diversity and beauty! The jewelry industry has become facinated with its beauty and many colors in all shades of the rainbow.

Jade on todays market is primarily composed of Nephrite; Jadeite Jade has become quite rare and in its emerald-green, translucent form is referred to as Imperial Jade or "gem jade". A small amount of cromium in Jadeite accounts for the color of Imperial Jade. Other color-based names for Jadeite Jade are Yunan Jade, for a uniquely appearing dark green, semitranslucent Jade, Apple Jade for apple (yellowish green) green Jade, and Moss-in-Snow for white Jade with vivid green spots and streaks. Nephrite and Jadeite Jade ranges in color from a somewhat greasy-appearing, white to dark and light shades of green, gray, blue-green, lavender, yellow, orange, brown, reddish-brown, and black. An important dark green variety of Nephrite is sometimes known as "spinach Jade". The chromophore in all Nephrite Jades is usually iron. Nephrite jade is usually opaque to translucent in thinner pieces. This particular Jade used in this piece is a shade of yellow. The name Jade has been, and continues to be, applied to a variety of materials that superficially or closely resemble Jade but are not composed of either Jadeite or Nephrite. So as the old saying gos "Buyer Beware !".

MOOKAITE - One of the Australia Stones !

Mookaite is actually a fossilifzed ferous sedimentary rock. The correct geological term for the formation that Mookaite occurs in is " Windalia Radiolarite." This stunning multi-colored stone is found in the Kennedy Ranges near Gascoyne Junction, which is about 100 miles inland from the coastal town of Carnarvon, in Western Australia. Perth, the capital of Western Australia, is about 600 miles to the south.

The "Windalia Radiolarite" consists of varicolored radiolarian commonly occuring in outcrops. Associated with the Mookaite in many locations are imprints of Ammonites. Stratigraphic relationships with adjacent areas, indicate that the "Windalia Radiolarite" formed originally on a marine shelf. Microscopic examination of the radiolarite has shown that this rock consists principally of the remains of tiny organisms known as 'radiolaria', which possessed an unusual skeletal structure of opaline silica. Countless numbers of these microscopic animals were deposited as sediment in the shallow waters, near shore area of ancient seas. When the seas retreated, these sediments were cemented into solid rock by silica carried in groundwater, either from the radiolaria themselves or from weathered rocks nearby.

The name "Mookaite" is derived from the locality where the rock is found, namely 'Mooka Creek'. According to local Aboriginaes, "mooka" means "running waters", no doubt in reference to the many fresh water springs that feed Mooka Creek in the rainy season.

Mookaite is many times incorrectly called mookite, mookalite, mookerite, mook, mook jasper, moukaite, moakite, moukalite or mouakite.

Mookaite can be correctly described as Chert, Opalite, Chalcedony or a combinations of two or of all three. The amount of silica in the material determines its physical description. This creates difficulties when digging Mookaite as the more Opaline in the rock, the more brittle it becomes. In this form, it is useless for cutting, as the lightest hit will cause it to fracture. The best material is the Chalcedonic variety. It generally occurs as nodules, large and small, lying in decomposed radiolarian clay beneath the floor of Mooka Creek. It appears that the silica rich and mineralised solutions have seeped through the radiolarite beneath the floor of the usually dry Mooka Creek bed. These solutions have concentrated in various locations and collected as nodules and sheets of the multi-colored Chalcedony variety, or better yet, gem quality Mookaite. Subsequently, the radiolarite with less silica has decomposed into beds of soft white clay which now surround the stunning nodules. Unfortunately there is a fair degree of underground water lying and running through these clay beds which make it extremely messy and difficult to dig out the good Mookaite from under the dry creek bed.