Tag: Green

Basalt as Colorant in Celadon Glazes

Basalt as Colorant in 2 Base Recipes.
Basalt as Colorant in 2 Base Recipes.

More local Basalt. Here used as colorant in high fire celadon glazes. On the top left, the raw material which was collected from various places throughout Idaho and Utah (and all mixed together), bottom left the homogenous, calcined, milled, sieved, and dried material ready for glaze.

In this set the basalt is supplying the iron necessary for that timeless celadon blue. Its also bringing significant additions of magnesium and calcium to the recipe. The % of basalt here ranges from 0 to 10% in 2.5% steps – applied to a dark stoneware and porcelain tiles.

This series were fired in a very fast and simple cone 10 reduction firing with a very basic reduction cool. 6 hours start to finish, in a small fiber test kiln — Heavy body redux for 30 min @ ^012-^08, then light redux to ^6, then a medium redux to ^10. At soft cone 11 I crash cooled a few hundred degrees, turned the air and gas down, dampered in, and put the kiln into about a -4°/minute cool, periodically opening the door to quickly crash cool -30 or -50 degrees until 1400, then shutting everything off. In some cases reduction cooling will effect the color and quality of the glazes significantly, but here it only effected the stoneware – keeping the iron oxide on the surface in its black reduced form. A good reduction firing will yield these glaze colors with no special effort cooling – here the RC was strictly for a darker stoneware color.

The Recipes

Fiske’s Tichane Chun
Custer Feldspar 48
Silica 31
Calcium Carb. 20
Bone Ash 1
(Iron Oxide 1.5)
— A range .5 to 3% Iron Oxide gives a similar spectrum of blue as the basalt does here – different flavors of Iron bearing materials yield different flavors of glaze, obviously. I’ve tried probably more than 50 kinds of iron over the years – try what you have and figure out what flavor you like best!

Fiske's Tichane Chun with 1.5% Red Iron Oxide. Fired to C10 in Reduction.
Fiske’s Tichane Chun with 1.5% Red Iron Oxide. Fired to C10 in Reduction.

Fiske’s (Pinnell Clear) PC Celadon
Custer Feldspar 25
Grolleg Kaolin 20
Calcium Carb. 20
Silica 35
(Spanish Iron Oxide .85)

Fiske's PC Celadon with a range of 0%-2.55 Red Iron Oxide. Fired in C10 Reduction.
Fiske’s PC Celadon with a range of 0%-2.55 Red Iron Oxide. Fired in C10 Reduction.

 

Moldavite

Imagine a sand pit getting hit directly with a gigantic-ass meteorite. Then imagine green glass gemstones raining back down amidst all the other debris. Similar to Fulgurite in some respects (Sand getting turned instantly into glass) Moldavite is the result of instant metamorphosis due to a crazy impact. They’re also quite beautiful to look at.

Moldavite
Moldavite

 

From Wikipedia:

Moldavite (Czech: Vltavín) is an olive-green or dull greenish vitreous substance possibly formed by a meteorite impact. It is one kind of tektite. They were introduced to the scientific public for the first time in 1786 as “chrysolites” from Týn nad Vltavou in a lecture by professor Josef Mayer of Prague University, read at a meeting of the Bohemian Scientific Society (Mayer 1788). Zippe (1836) first used the term “moldavite” derived from the town of Moldauthein (Czech: Týn nad Vltavou) in Bohemia (the Czech Republic), from where the first described pieces came from.

 

46 CT for 100.00$ on eBay
46 CT for 100.00$ on eBay

Moldavite’s bottle-green glass colour led to its being commonly called Bouteillen-stein, and at one time it was regarded as an artificial product, but this view is opposed to the fact that no remains of glassworks are found in the neighbourhood of its occurrence; moreover, pieces of the substance are widely distributed in Middle to Upper Miocene and younger fluvial clays and gravelly sands in Bohemia and Moravia.

 

In 1900, F. E. Suess pointed out that the gravel-size moldavites exhibited curious pittings and wrinkles on the surface, which could not be due to the action of water, but resembled the characteristic markings on many meteorites. Boldly attributing the material to a cosmic origin, he regarded moldavites as a special type of meteorite for which he proposed the name of tektite. However, for a long time, it was generally believed to be a variety of obsidian. Because of their difficult fusibility, extremely low water content, and its chemical composition, the current overwhelming consensus among earth scientists is that moldavites were formed 15 million years ago during the impact of a giant meteorite in present-day Nördlinger Ries. Splatters of material that was melted by the impact cooled while they were actually airborne and most fell in central Bohemia—traversed by Vltava river (German: Moldau). Currently, moldavites have been found in area that includes southern Bohemia, western Moravia, the Cheb Basin (northwest Bohemia), Lusatia (Germany), and Waldviertel (Austria).[1] Isotope analysis of samples of moldavites have shown a beryllium-10 isotope composition similar to the composition of Australasian tektites (Australites)and Ivory Coast tektites (Ivorites). Their similarity in beryllium-10 isotope composition indicates that moldavites, Australites, and Ivorites consist of near surface and loosely consolidated terrestrial sediments melted by hypervelocity impacts.

 
99 % of all moldavite finds have provided the South Bohemian localities, 1% were found in South Moravian localities. Only tens of pieces were found in the Lusatian area (near Dresden), Cheb basin area (West Bohemia) and Northern Austria (near Radessen). Principal occurrences of moldavites in Bohemia are associated with Tertiary sediments of the České Budějovice and Třeboň Basins. The most prominent localities are concentrated in a NW-SE strip along the western margin of the České Budějovice Basin. Majority of these occurrences are bound to the Vrábče Member and Koroseky Sandy Gravel. Prominent localities in the Třeboň Basin are bound to gravels and sands of the Domanín Formation. In Moravia, moldavite occurrences are restricted to an area roughly bounded by the towns of Třebíč, Znojmo and Brno. Taking into account the number of pieces found, Moravian localities are considerably less productive than the Bohemian ones; however, the average weight of the moldavites found is much higher. The oldest (primary) moldavite-bearing sediments lie between Slavice and Třebíč. Majority of other localities in southern Moravia are associated with sediments of Miocene as well as Pleistocene rivers that flowed across this area more or less to the southeast, similar to the present streams of Jihlava, Oslava a Jevišovka.

 

From the Moldavite museum in Český Krumlov, Czech Rep
From the Moldavite museum in Český Krumlov, Czech Rep
From the Moldavite museum in Český Krumlov, Czech Rep
From the Moldavite museum in Český Krumlov, Czech Rep

Aurora over Iceland

“Auroras appearing from a glacier as if it was a volcano.” Awesome.

From Apod.nasa.gov

Explanation: What’s happening in the sky? On this cold winter night in Iceland, quite a lot. First, in the foreground, lies the largest glacier in Iceland: Vatnajokull. On the far left, bright green auroras appear to emanate from the glacier as if it was a volcano. Aurora light is reflected by the foreground lake Jökulsárlón. On the far right is a long and unusual lenticular cloud tinged with green light emitted from another aurora well behind it. Just above this lenticular cloud are unusual iridescent lenticular clouds displaying a broad spectral range of colors. Far beyond the lenticular is the setting Moon, while far beyond even the Moon are setting stars. The above image was captured in late March of 2012.

Credit: Stéphane Vetter
Credit: Stéphane Vetter