Celadonite
- Celadonite
Seladonite ( engl: Celadonite ), synonym or as a pigment also known as green earth (mainly consisting of celadonite and glauconite mixture ), Veronesererde, Veronesergrün, Tyrolean earth known is a commonly occurring mineral from the mineral class of " silicates and Germanates ". It crystallizes in the monoclinic crystal system with the chemical composition K (Mg, Fe2 ) ( Fe3 , Al) [( OH) 2 | Si4O10 ] and developed predominantly earthy and massive mineral aggregates, rarely but also tiny, mica-like, flaky crystals of light green to blue-green color and white line color. Often we find the seladonite also intimately intergrown with heulandite or stilbite and overseeing this normally colorless minerals for a smooth, sea -green color.
Seladonite served in ancient times as a green pigment.
Etymology and history
Was first described in 1847 by Ernst Friedrich seladonite Glocker, who named the mineral because of its characteristic color from the French word " céladon " for sea green.
For the seladonite three type localities are given: Planitz in Saxony ( Germany ), " Malga Canalece " in Brentonico and " Tierno - Besagno " at Mori at Mount Baldo in the Italian province of Trentino. The reason for this is that for the determination of mineral several samples had to be drawn from the above-mentioned localities.
Classification
In the out-dated since 2001, but still in use 8th edition of the classification of minerals according to the Strunz seladonite belongs to the department of " layer silicates ( phyllosilicates ) " and then to " mica group, subgroup celadonite - muscovite - series".
Since the revision of the Strunz'schen Mineral classification in the 9th edition of the phyllosilicates are precisely divided according to the structure of the silicate layers and the mineral is found in accordance with the division of the " layer silicates ( phyllosilicates ) with mica sheets, composed of tetrahedral and octahedral nets " where it a member of the glauconite group with the system no. 9.EC.15 is.
The classification of minerals according to Dana sorted the seladonite also in the Department of phyllosilicates and also in the scheme of Dana is further clarified by the crystal structure. However, here the subdivision is described as " layer silicates with layers of six-membered rings with 2:1 layers ". The mineral is found there in the " mica group (muscovite - subgroup ) " with the system no. 71.02.02a.
Education and Locations
Seladonite is likely to form in basic volcanic rocks by hydrothermal processes, where it replaces existing primarily, iron-and magnesium-containing silicates. Accompanying minerals include calcite, chlorite different, different heulandites, clinoptilolite, laumontite, montmorillonite, prehnite and quartz.
Celadonite occurs in different localities and by locality shows different nuances as span, bluish and celadon green, olive, apple - or gray-green. The bestfarbigen Seladonite come from Monte Baldo near Verona, where they are to be found in large masses.
Other sites are in Trentino ( Val di Fassa ) and Tyrol (Zillertal ), am Harz, Thuringia, Bohemia, Poland and Hungary, in Scotland ( Scuir Mohr ) and the Faroe Islands ( Streymoy, Suduroy ). Deposits in North America are, inter alia, in Oregon ( John Day Formation), at Mt Rainier National Park (Wash. ), California ( Red Rock Canyon ) and Nicaragua as well as in Japan ( prefectures Miyagi, Yamagata, Kamogawa and Chiba ). Worldwide, seladonite so far (as of 2010) are detected at around 200 localities.
A well-known locality is also the Monte Altissimo di Nago, the 2079 m high north summit of Monte Baldo with a seladonite digestion, in which the in ancient times used as " Terra Verde " pigment " Green Earth " is present.
Crystal structure
Seladonite crystallizes in the monoclinic space group C2 / m or C2 with lattice parameters a = 5.22 Å; b = 9.05 Å; c = 10.20 Å and β = 100.4 ° and two formula units per unit cell.
Use
Celadonite or green earth since antiquity had already served as a pigment and is still fine elutriated at very durable, color-fast and harmless colorants for paints and paintings, processed both as oil paint, as well as distemper. Due to excessive glow color is transformed into a beautiful brown.