Wave Hill, Northern Territory, AUSTRALIA
Wave Hill, Northern Territory is possibly the finest quality
gem grade prehnite in the world.
Prehnite is a phyllosilicate of calcium and aluminium. Fe3+ may
substitute aluminium in the structure.
Crystal System: Orthorhombic
Hardness: 6 - 6.5
Specific Gravity: 2.80 - 2.90
Fracture: Brittle as displayed
by most glass-like minerals.
Lustre: Vitreous to pearly.
Colour: Colourless to all shades of green,
yellow and rarely
Luminescence: Fluorescent SW Blue
Diaphaneity: Translucent to sub-transparent
Habit: Globular, reniform, sometimes stalactitic.
Prehnite is found in many countries worldwide but gem grade prehnite is rare.
Prehnite was discovered in the Wave Hill area of Northern Territory
many years ago and during the 1960s, several fossickers sold
a few Kgs of low to medium grade material to dealers in Victoria.
These first shipments of prehnite were sent to Germany for carving
but nothing more was mined after those early shipments.
Prehnite is the first mineral to be named after a person. Prehnite was first
described in 1989 and named after a dutch Colonel Hendrik Von
Prehn (1733-1785) commander of the military forces of the Dutch
colony at the Cape of Good Hope. Prehnite often occurs with zeolites
and is mistakenly referred to as a zeolite.
During the 1970s, Gerald Pauley had the good fortune to gain permission
to access old mine reports at the Bureau of Mineral Resources in Darwin,
prior to it being blown away by Cyclone 'Tracey'. He discovered
articles about various gemstones near Wave Hill.
On the first trip to Wave Hill, in 1974, he realised the potential of the
area to produce fine quality prehnite and also identified other
gem and mineral reserves of possible economic significance; namely:
Agate, Amethyst, Smoky Quartz and Red Jasper (Chicken Blood Jasper).
After yearsof prospecting the area, in the early 1980's he discovered
what is believed to be the finest deposit of gem grade prehnite in
the world. In March 2013, Linna Huang purchased
the almost 10 Sq. Kilometre lease and commenced the first
full scale mining operation on the reserve.
Over years since the 1980s surface collecting produced a few Kgs of high
grade prehnite but after years of fossicking and hand collecting the
surface deposits were depleted. by observation, surface material
is highly crazed and faded due to the hostile extremes of temperature
in the semi-desert area where the lease is situated. Daytime
temperatures in the desert area can be as high as 35°C but
at night it can freeze. This cause the prehnite to fracture and
since the early discovery of the gem grade prehnite in the early
1980s no-one has seen true high grade prehnite.
Heavy earth moving equipment was brought in to open, and prove, the deposit.
The results were outstanding with the best quality prehnite ever
seen being uncovered a few centimetres below the surface. A further
10 centimetres down harder basalt was encountered and the equipment
failed to be effective in ripping the basalt efficiently. Prehnite
was found in the harder basalt but it will have to wait until
the next mining season. After cleaning a few tonnes of the mined
material we were excited too see the quality.
This fine prehnite will soon be available commercially on the international
market as high gem grade rough and as cut stone and in jewellery.