Depending upon the conditions, either nucleation or growth may be predominant over the other, and as a result, crystals with different sizes and shapes are obtained (Control of crystal size and shape constitutes one of the main challenges in industrial manufacturing, such as for pharmaceuticals).
For the region, see San Fernando Valley. San Fernando is a city located in the San Fernando Valley, in the northwestern region of Los Angeles County, California. It is completely surrounded by the City of Los Angeles.
The Los Angeles River, Rio Hondo, the San Gabriel River and the Santa Clara River flow in Los Angeles County, while the primary mountain ranges are the Santa Monica Mountains and the San Gabriel Mountains. The western extent of the Mojave Desert begins in the Antelope Valley, in the northeastern part of the county.