materialsscienceandengineering: Composites: Jesmonite Despite…

materialsscienceandengineering:

Composites: Jesmonite

Despite the name, jesmonite is not a mineral. Or, not exactly – jesmonite is a composite that consists of a gypsum-based material (a sulfate mineral made of calcium sulfate dihydrate) held together by a water-based acrylic resin.

As a material, jesmonite is known to be durable, fire resistant, and tough. As a composite its composition is loosely defined with the exact mix capable of alteration to improve the properties and appearance. The addition of pigments or metal powders is fairly common. It is a low hazard material capable of forming intricate shapes – either though casting or lamination – and after mixing jesmonite is in the form of a quick-setting liquid.

Mostly used in art, such as sculptures, jesmonite’s surface is often finished after the material sets and can be made to look like wood, stone, metal, or even leather. In addition to artwork, jesmonite is sometimes used in casting applications. 

Sources/Further reading: ( 1 – images 1 and 4 ) ( 2 – image 2 ) ( 3 ) ( 4 ) ( 5 )

(Image 4).

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Formations in Context (Or, What is It?)Some HiRISE images show…

Formations in Context (Or, What is It?)

Some HiRISE images show strange-looking formations. Sometimes it helps to look at Context Camera images to understand the circumstances of a scene—like this cutout from CTX 033783_1509—which here shows an impact crater with a central peak, and a collapse depression with concentric troughs just north of that peak. Our HiRISE picture is a close-up of one of those troughs, along with channels draining into the depression.

On the floor of the trough is some grooved material that we typically see in middle latitude regions where there has been glacial flow. These depressions with concentric troughs exist elsewhere on Mars, and their origins remain a matter of debate. 

Remains of Graeco-Roman temple discovered near Egypt’s Siwa Oasis

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An Egyptian archaeological mission from the Supreme Council of Antiquities has uncovered the remains of a Graeco-Roman temple while carrying our excavation work at the Al-Salam archaeological site, about 50km east of the Siwa Oasis.

Aymen Ashmawi, the head of the Ancient Egyptian Antiquities Department at the Ministry of Antiquities, said that the mission uncovered the front part of the temple as well as parts of its foundations, its main entrance and one-metre thick stones from its outer wall.

The outer wall leads to a front courtyard with entrances to chambers.

Ashmawi said he expects the rest of the temple to be excavated this year. 

The head of the archaeological mission Abdel-Aziz El-Demery said that during the removal of the debris from the site, the mission uncovered architectural elements including upper lintels decorated with scenes, as well as parts of corner pillars decorated with the egg-and-dart architectural device common in the Graeco-Roman era. Read more.