Nitrofurantoin (Macrodantin, Furadantin, Macrobid) is a drug available in three forms prescribed for the treatment or prevention of urinary tract infections (UTIs). Side effects, warnings and precautions, drug interactions, and patient information should be reviewed prior to taking any medication.
In this group the mineral is held together by the attraction between silica tetrahedra and other positive ions. Olivine and Garnet are examples of minerals within the independent tetrahedra group. Single chain silicates contain silica tetrahedra that are linked up in a chain by sharing two oxygen atoms. The most common single chain silicate is pyroxene. Double chain silicates form by sharing either two or three oxygen.
Quartz has a unique structure. Actually, there is another mineral that shares quartz's structure, and it is not even a silicate. It is a rare phosphate named berlinite, AlPO4, that is isostructural with quartz. The structure of quartz involves corkscrewing (helix) chains of silicon tetrahedrons. Prasiolite is a leek-green gemstone variety that is rare in nature but is created by heating Amethyst from certain locations. 2  Rock crystal is the clear variety that is also used as a gemstone. 3  Rose quartz is a pink to reddish pink variety. 4  Smoky quartz is the brown to gray variety.