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In the MRC, helvine-group minerals occur in pegmatite miarolitic cavities and are represented by the minerals genthelvite [Be SB 3 sb Zn SB 4 sb (SiO SB 4 sb ) SB 3 sb S] and danalite [Be SB 3 sb Fe SB 4 sb SP 2+ sp (SiO SB 4 sb ) SB 3 sb S]. These pegmatites are often macroscopically indistinguishable because they are composed of the same major mineral assemblages: quartz and microcline ± albite, with a notable absence of mica minerals. In all these units, beryl, the most common beryllium mineral, was never a crystallizing phase; instead, a suite of less-common late-stage primary and secondary Be-bearing minerals are present. Most notably, beryl was never a crystallizing phase; instead, other Be-minerals including bertrandite, phenakite, bazzite, gadolinite, hingganite, and helvine-group minerals are the primary Be-bearing minerals. [Extracted from the article]

Features that are visible in the rhyolitic lava flow at Obsidian Cliff include pristine volcanic glass (black), flow banding (marked by trails of small, gray and pink spherulites), coarse pink spherulites, and lithophysae (large tan cavities). For example, lithophysal cavities that occur in spherulite cores are interpreted to be preexisting vesicles around which spherulite crystallization proceeded ([9]). Spherulites are clusters of radiating crystals, generally alkali feldspar and quartz polymorphs, that form either partial or complete spheres and are most distinct when present in obsidian. Compositional gradients surrounding spherulites in obsidian and their relationship to spherulite growth and lava cooling. [Extracted from the article]

The article presents information on minerals, found in Miarolitic Pegmatites in the Stove Mountain area of Colorado. It says that many attractive specimens of quartz, microcline, albite, and fluorite, along with opaque brown zircons with curved faces, have been found in this area. It focuses on the importance of understanding the geology for determining the occurrence of rare accessory minerals. It also focuses on occurrence, morphology, and chemistry of some accessory minerals in this area.

The article focuses on the Sunset Crater Volcano National Monument in Northern Arizona. The study of mineral composition of the volcano show that it has six fumarole deposits which are active during its waning stages. The fumarole deposits revealed diverse color zones that surround the fumarole vents which can be attributed to the rapidly increasing fugacity. It also offers the history of the volcano, its volcanic activity, and its physical features.