One aspect relates to a process for the preparation of a quartz glass body, including providing a silicon dioxide granulate, wherein the silicon dioxide granulate was made from pyrogenic silicon dioxide powder and the silicon dioxide granulate has a BET surface area in a range from 20 to 40 m.sup.2/g, making a glass melt out of silicon dioxide granulate in an oven and making a quartz glass body out of at least part of the glass melt. The oven has at least a first and a further chamber connected to one another via a passage. The temperature in the first chamber is lower than the temperature in the further chambers. On aspect relates to a quartz glass body which is obtainable by this process. One aspect relates to a light guide, an illuminant and a formed body, which are each obtainable by further processing of the quartz glass body.

A method of producing a glass briquette in which reclaimed glass fines are mixed with a binder material to create a mixture. The mixture is subsequently compressed in a chamber to form a briquette having the shape of the interior of the chamber. The reclaimed glass includes glass fines of a size of smaller than 10 mm. The method is performed without melting the glass fines such that the resulting briquette contains the discrete glass fines held in the binder and may be used as a furnace ingredient for later glass product production. The glass briquette may contain other batch ingredients required in the production of glass.

A quartz glass crucible (1) has a structure wherein a peak of a distribution of a total concentration of Na, K, and Ca in a depth direction from an inner surface (10i) of the crucible is present at a position deeper than the inner surface (10i). In an exemplary embodiment, the quartz glass crucible is capable of improving the yield of a silicon single crystal by suppressing peeling-off of brown rings.

A quartz glass crucible (1) includes: a crucible body (10) made of silica glass; and a crystallization-accelerator-containing layer (13) formed on an outer surface of the crucible body (10). A concentration of a crystallization accelerator contained in the crystallization-accelerator-containing layer (13) is 1.0×10.sup.13 atoms/cm.sup.2 or more and 4.8×10.sup.15 atoms/cm.sup.2 or less. The quarts glass crucible is intended to be capable of not only enduring a single crystal pulling-up process that takes a very long time, such as multi-pulling, but also stably controlling the oxygen concentration and crystal diameter of a silicon single crystal by eliminating a gap between the carbon susceptor and the crucible as much as possible.

A tubular member for an exhaust gas treatment device according to at least one embodiment of the present invention includes: a tubular main body made of a metal; and an insulating layer formed at least on an inner peripheral surface of the tubular main body. The insulating layer contains glass containing a crystalline substance, and the glass contains silicon, boron, and magnesium.

Disclosed herein is a glass composition including, based on a total weight of the glass composition, 49 wt % to 59 wt % of SiO.sub.2, 9.5 wt % to 14.5 wt % of Al.sub.2O.sub.3, 19 wt % to 35 wt % of B.sub.2O.sub.3, 2 wt % to 5 wt % of CaO, 0.25 wt % to 3 wt % of ZnO, 0 wt % to 1 wt % of MgO, 0 wt % to 1 wt % of TiO.sub.2, 0 wt % to 3 wt % of ZrO.sub.2, and 0.1 wt % to 3.5 wt % of MnO. Also disclosed herein are a glass fiber and a glass article which include the glass composition.

An optical fiber containing alkali metal elements or the like in which Rayleigh scattering loss can be reduced is provided. An optical fiber includes a core composed of silica glass and a cladding which surrounds the core, has a refractive index lower than a refractive index of the core, and is composed of silica glass containing fluorine. The core contains a first group of dopants and a second group of dopants having a diffusion coefficient lower than a diffusion coefficient of the first group of dopants. The difference between the maximum value and the minimum value of residual stress in the optical fiber is 150 MPa or less.

A glass has a low ratio of density ρ and refractive index n.sub.d. The glass has a refractive index n.sub.d in a range of 1.80 to 2.00, an internal transmission of at least 80% (450 nm, 10 mm), a dispersion v.sub.d of 19.0 to 27.0, and a ratio ρ/n.sub.d of <1.97.

A glass element has, per kg of glass, 50 or fewer inclusions having a size of 2 μm to 10 μm. The glass element can be made of borosilicate glass.

A glass article is designed at least in part in the form of a glass tube element including at least one shell which encloses at least one lumen. For at least one light transmission analysis of the glass article, a ratio of an average amplitude transmission factor and a specific amplitude transmission factor is greater than 1.00001.