Celestite from Madagascar

Write By: tmmadmin Published In: Mineral Species Created Date: 2014-12-02 Hits: 9519 Comment: 0


12" 3-Chamber celestite geode, Sakoany, Madagascar

Since 1967, the Sakoany area on the northwestern coast of Madagascar has yielded hundreds of tons of geodes lined with beautiful blue celestite (also known as celestine) crystals, the world's finest examples of the species. The geodes and crystals from this area are very beautiful and colorful, making them very popular with mineral collectors.


Celestite crystals to 2.5" inside a geode, Sakoany, Madagascar

LOCATION
The celestite deposit is located in Sakoany village, Kaominina Katsepy, Distrikan' i Mitsinjo, Faritra Boeny, Faritanin' i Mahajanga, Madagascar. To get there, you take a boat from Majunga across Bamekota Bay to Katasepy, then a 4WD vehicle south for 12km. From there it is a 10km hike to the village.


8.5" Celestite geode, Sakoany, Madagascar

HISTORY
Celestite was named for its pale sky-blue color (from the Latin term caelestis) by Abraham Werner in 1798. The Sakoany deposit was first discovered by a cattle herder who found some crystals that had weathered out close to the shore of the bay. In 1967, villagers started mining the deposit and continued into the 1970s. Mining apparently stopped then for about 10 years, and didn't resume until the early 1980s. Since then there has been a continuous supply of superb celestite crystal geodes and groups, and the deposit shows no signs of being exhausted.


11" Celestite geode, Sakoany, Madagascar

GEOLOGY
celestite at Sakoany is found in two layers in a Lower Paleocene (65 MYO) sedimentary deposit. The upper zone, which is 2 to 5 meters thick, produces 2 cm crystals in clusters to 10 cm. The lower zone, which produces geodes from 10 to 20 cm (and up to 1 meter) in diameter, is encountered at a depth of about 10-15 meters. The thickness of this deposit is not known. The crystals are found lining cavities in sandstone, thus forming geodes.


6" Celestite geode, Sakoany, Madagascar

MINING
The Sakoany deposit is not really a mine - it is a collection of hundreds of individual pits about 5-10 meters apart dug by hand by artisanal miners in a 10-square kilometer area to the northwest of Sakoany village. Narrow, very neat rectangular pits are dug out, with narrower shafts continuing downward providing a series of benches as the pit is dug deeper. Toe holds are dug in the walls for the miners to climb in and out of the mines. Geodes and waste rock are lifted from the bottom to the next highest level and then upward to the top of the mine. Ground water is hauled out in buckets with a rope. Once the miners reach the lower zone, they continue downward until they hit the water table. Then they dig out in all directions and remove the geodes. This continues until the air becomes bad, or when they stop finding geodes and the pit is then abandoned. The geodes are usually taken out intact, and opened later back at the village. There is no mining during the rainy season because the pits fill with water.


Celestite crystals inside a geode, Sakoany, Madagascar

MINERALOGY
Celestite is strontium sulfate, or SrO4. It has a glassy luster and chonchoidal fracture, with a hardness of 3-3.5. At Sakoany, celestite is found in transparent to translucent gemmy crystals that are colored blue to sky-blue. The blue color of celestite has been attributed to the presence of minute amounts of gold. Crystals are found in two habits: blocky orthorhombic prisms and elongated, bipyramidal, tapering, pointed crystals.


11" Celestite geode, Sakoany, Madagascar

USES
Celestite is used to make fireworks, because it burns with a bright red color. It is also used in the pharmaceutical and chemical industries, and was an ingredient in the glass used in TV sets and cathode ray tubes


3" Celestite crystal inside a geode, Sakoany, Madagascar

OTHER LOCALITIES
The world's largest geode was found near the village of Put-in-Bay, Ohio, on South Bass Island in Lake Erie. It is a celestite geode 35 feet in diameter with crystals up to 18" wide. celestite is also found in Ohio, Kansas, Michigan, New York, Colorado, Death Valley California and Texas. It is commonly found associated with sulfur in Sicily and in red, cloudy crystals near Toronto, Canada. The best celestite crystals in the world come from Madagascar.

LOCALITY PHOTOS

Photos by Rock Currier

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