Gambar Pilihan

Gas adi merujuk kepada gas dalam Kumpulan 18 Jadual berkala yang mempunyai sifat lengai, tidak reaktif, tidak berwarna dan tidak bertindakbalas dengan bahan kimia lain. Gas adi banyak digunakan dalam sektor perindustrian. Enam gas adi wujud secara semula jadi iaitu Helium (He), Neon (Ne), Argon (Ar), Kripton (Kr), Xenon (Xe) dan Radon (Rn).

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Tahukah Anda?

... that sérandite (pictured) was discovered in Guinea, described in a French journal, and the type material resides in Washington, D.C.?

Sérandite, also serandite[citation needed], is a mineral with formula Na(Mn2+,Ca)2Si3O8(OH). The mineral was discovered in Guinea in 1931 and named for J. M. Sérand. Sérandite is generally red, brown, black or colorless.

Description

Sérandite is transparent to translucent and is normally salmon-pink, light pink, rose-red, orange, brown, black, or colorless; in thin section, it is colorless.[1] Octahedrally bonded Mn(II) is the primary contributor to the mineral's pink colors.[3]

Crystals of the mineral can be prismatic to acicular and elongated along [010], bladed, blocky, or tabular and flattened on {100}, occur as a radiating aggregate, or have massive habit.[1] Sérandite is a member of the wollastonite group and is the manganese analogue of pectolite.[2]

History

Sérandite was discovered on Rouma Island, part of the Los Islands in Guinea.[2] The mineral was described by À. Lacroix in the journal Comptes Rendus hebdomadaires des séances de l’Académie des Sciences.[4] He named it sérandite in honor of J.M. Sérand, a mineral collector who helped in the collection of the mineral.[2]

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Today's featured picture

On July 25, 1976, the Viking 1 spacecraft captured images of a mesa in the Cydonia region of Mars with the appearance of a humanoid face (see inset), which led to much speculation about life on Mars. In 2007, high-resolution images taken by the Mars Reconnaissance Orbiter of the same structure definitively showed that the face was merely an optical illusion known as pareidolia.
Photo: NASA/JPL/University of Arizona

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Arctic Circle transformed into ghostly world

In what appears to be the set of a science fiction movie, photographer Niccolo Bonfadini has captured ghostly images of trees buried under a foot of snow in the Arctic Circle. Snow and frost become so thick the entire landscape is transformed into an otherworldly planet.

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Today's featured picture

Nickel

Electrolytically refined pure (99.9%) nodules and a 1 cm3 cube of nickel, a silvery-white lustrous transition metal with a slight golden tinge. The nodules have visible green, crystallized nickel-electrolyte salts in the pores. Native nickel is rarely found on Earth's surface, being mostly confined to the interiors of larger nickel–iron meteorites.
Photo: Alchemist-hp

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