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Fulgurites are usually fragile, making the field collection of large specimens difficult. Fulgurites can exceed 20 centimeters in diameter and can penetrate deep into the subsoil , sometimes occurring as far as 15 m (49 ft) below the surface that was struck, [ 10 ] although they may also form directly on a sedimentary surface. [ 11 ]
Sea glass is physically polished and chemically weathered glass found on beaches along bodies of salt water. These weathering processes produce natural frosted glass. [1] Sea glass is used for decoration, most commonly in jewellery. "Beach glass" comes from fresh water and is often less frosted in
Rounded glass at the beach. The beach is now visited by tens of thousands of tourists yearly. [3] Collecting is discouraged by State Park Rangers on the section of "Glass Beach" adjacent to the state park, [2] where they ask people to leave what little glass is left for others to enjoy, although most of the sea glass is now found on the other two glass beaches outside the state park area.
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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]
Rhyolites that cool too quickly to grow crystals form a natural glass or vitrophyre, also called obsidian. [13] Slower cooling forms microscopic crystals in the lava and results in textures such as flow foliations, spherulitic, nodular, and lithophysal structures. Some rhyolite is highly vesicular pumice. [5]
Crystals are rare but will form fibrous, elongated crystals either oriented parallel or radial to each other. Crystals may also be acicular, resembling needles (Anthony et al., 2005). [ 16 ] The point group of ulexite is 1, which means that the crystals show very little symmetry as there are no rotational axes or mirror planes.
The physical origin of the non-Arrhenius behavior of fragile glass formers is an area of active investigation in glass physics. Advances over the last decade have linked this phenomenon with the presence of locally heterogeneous dynamics in fragile glass formers; i.e. the presence of distinct (if transient) slow and fast regions within the material.