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In terms of crystal habit, diamonds occur most often as euhedral (well-formed) or rounded octahedra and twinned, flattened octahedra with a triangular outline. Other forms include dodecahedra and (rarely) cubes. There is evidence that nitrogen impurities play an important role in the formation of well-shaped euhedral crystals. The largest ...
Very few samples of obsidian are nearly colorless. In some stones, the inclusion of small, white, radially clustered crystals (spherulites) of the mineral cristobalite in the black glass produce a blotchy or snowflake pattern (snowflake obsidian). Obsidian may contain patterns of gas bubbles remaining from the lava flow, aligned along layers ...
Cut glass wine glass made of lead glass. Lead glass, commonly called crystal, is a variety of glass in which lead replaces the calcium content of a typical potash glass. [1] Lead glass contains typically 18–40% (by mass) lead(II) oxide (PbO), while modern lead crystal, historically also known as flint glass due to the original silica source, contains a minimum of 24% PbO. [2]
Physicists in Finland are the latest scientists to create “time crystals,” a newly discovered phase of matter that exists only at tiny atomic scales and
Natrolite showing acicular crystal habit. Acicular, in mineralogy, refers to a crystal habit composed of slender, needle-like crystals. Crystals with this habit tend to be fragile. Complete, undamaged acicular specimens are uncommon. Needle-shaped acicular millerite crystals on white quartz
A crystal's crystallographic forms are sets of possible faces of the crystal that are related by one of the symmetries of the crystal. For example, crystals of galena often take the shape of cubes, and the six faces of the cube belong to a crystallographic form that displays one of the symmetries of the isometric crystal system. Galena also ...
The most common crystal structure of diamond is called diamond cubic. It is formed of unit cells (see the figure) stacked together. Although there are 18 atoms in the figure, each corner atom is shared by eight unit cells and each atom in the center of a face is shared by two, so there are a total of eight atoms per unit cell. [16]
A very pure crystal of calcite can split a beam of sunlight into dual images, as the polarized light deviates slightly from the main beam. By observing the sky through the crystal and then rotating it so that the two images are of equal brightness, the rings of polarized light that surround the sun can be seen even under overcast skies.