is a variety of Calcite pseudomorphed after Ikaite.
A pseudomorph is a mineral with the external crystal form of one mineral and the internal chemistry of another.
Ikaite is the hydrated version of Calcite, or Calcite
is the dehydrated version of Ikaite. The chemical
formual for Ikaite is CaCO3·6H2O.
The chemical formual for Calite is CaCO3,
the same as for Ikaite but without the H2O.
Ikaite readily dehydrates to Calcite in temperatures
above 8°C and is typically found in near-freezing
water in deep sea locations or locations of cold seeps.
A cold seep, sometimes called a cold vent, occurs over
cracks and fissures in the sea floor caused by tectonic
activity. These seeps allow hydrogen sulfide, methane
and other hydrocarbon-rich fluids to "seep"
from the earth. Ikaite is formed from the calcium carbonate-rich
mixture at the seeps.
Ikaite is removed from its natural cold water environment,
it rapidly disintegrates into anhydrous calcium carbonate
and water, earning it the nickname "the melting
mineral". The resulting pseudomorph of Calcite after Ikaite is called "Glendonite"
after the location where it was first reported in 1905,
Glendon, New South Wales, Australia. Ikaite is named
for the type locality at the Ikka Fjord (formerly spelled Ika), Greenland.
most well know form is a radial arrangement of brown,
reddish-brown or cinnamon-brown crystals. It has also been called the
"rose rock" referring to the radial arrangement of the crystals giving
it a flower-like appearance. Some have said the "spikey" habit of the crystals looks more like a pine cone.
Calcite psuedomorphs after Ikaite are known by several
other names as well. These names are often after specific
locations such as Jarrowite named after Jarrow,
Northumberland, UK, and Fundylite named for the
Bay of Fundy, Nova Scotia, Canada. Other names are regionally
derived referring to the crystal's unusual shapes
such as Gersternkorner which is German for barleycorn
and Gennoishi which is hammerstones in
Japanese and Molekryds meaning mole cross
in Danish. There are also the names White Sea
Hornlets from the White Sea and Kola Peninsula,
Russia and Thinolite from the Greek word thinos,
meaning shore, from of the occurance in the
tufa of Mono Lake, California, USA.
distribution: in addition to the "type locality"
at Glendon, New South Wales (NSW), Australia, Glendonite
is also found at these locations in Australia: Hunter
Valley, Durham County, NSW; Wallaby Gully, Quarrobolong,
Northumberland County, NSW and Yerila Creek, North Flinders
Ranges, South Australia. In Canada at Eureka, Ellesmere Island, Nunavut Territory.
In Japan at Koudo, Ueda City, Nagano prefecture, Chubu region, Honshu Island.
In Russia at the Olenitsa River, White Sea Coast, Kola Peninsula, Murmanskaja Oblast', Northern Region.
In the USA at Mono Lake, Mono County, California; and
in Washington at Altoona, Wahkiakum County, and Five Mile Quarry, Porter, Grays Harbor County.