- Aphanites (adj. aphanitic; from Ancient Greek αφανης (aphanḗs) ‘invisible’) are igneous rocks that are so fine-grained that their component mineral crystals are not visible to the naked eye (in contrast to phanerites, in which the crystals are visible to the unaided eye). This geological texture results from rapid cooling in volcanic or hypabyssal (shallow subsurface) environments. As a rule, the texture of these rocks is not the same as that of volcanic glass (e.g., obsidian), with volcanic glass being non-crystalline (amorphous), and having a glass-like appearance.
- Gamma Hydrae (stars.astro.illinois.edu)
Skipping over obscure (at least in brightness) fourth magnitude Beta Hydrae (the southernmost of Hydra’s outlining stars), exact third magnitude Gamma Hydrae (3.00) comes in at number two, just beating out a host of slightly lesser stars (such as Nu, Zeta, Pi, and Epsilon).
- Mineral (Wikipedia)
In geology and mineralogy, a mineral or mineral species is, broadly speaking, a solid substance with a fairly well-defined chemical composition and a specific crystal structure that occurs naturally in pure form.