Specimen #2388

Name: Mookaite

Type: Gem

Locality: Brazil

Favorite? N

Fluorescent? N

Size: 15.25 mm

Weight: 12.62 ct

Acquired: 2012-01-26

Source: Arkenstone Auction

Label: N

Comment: According to mindat.org, "The term 'Mookaite' is an unofficial, locally coined name for a silicified porcelanite which forms in the weathering profile of a geological formation known as Windalia Radiolarite (WR), a Lower Cretaceous siltstone that outcrops over much of the Carnarvon Basin in Western Australia. Mookaite is variously, and incorrectly, described as chert, opalite, chalcedony or combinations of the three. From a strictly geological perspective however, Mookaite is best defined as a silicified type of WR whose silification is opaline to chalcedonic." For reference, Porcelanite is defined as "a rock, semivitrified clay or shale, somewhat resembling jasper, composed of mullite and other high-temperature silicate and oxide minerals". This stone is an attractive "Mookaite" stone with warm golden and cream colored hues and a "Square Cushion Cabochon" cut. One of the few stones of this material that I have offered in the auctions.

Minerals:

There is one picture on file

M02388-01.jpg:

Mookaite, Brazil - FOV: 15.5 x 23.3 mm (12.62 cts)