The cell wall surrounds the cell membrane in plant cells, bacteria, and some fungi. In plant cells, the cell wall is composed of cellulose. In bacteria, the wall is made mostly of polypeptides (protein) or polysaccharides (carbohydrates). The cell wall provides support and protection and is responsible for giving plant cells their shape. Another important structure found only in eukaryotic cells is the nucleus . This struc-ture contains the genetic information and is the control center of the cell. Protecting the nucleus is a double-membrane called the nuclear envelope , which, like the plasma membrane, is semi-permeable.
Welcome to the Bisha Mining Share Company. Bisha Mining is an Eritrean company formed for the development and operation of the Bisha Mine in western Eritrea. It is owned by Nevsun Resources Ltd. (60%) and the Eritrean National Mining Corporation (ENAMCO) (40%). The Bisha Mine is a high-grade copper, gold, silver and zinc mine that commenced production in February 2011.
Gabbro-norite (polished slab), marketed as Impala Black Granite, Bushveld Complex. It is composed principally of grayish plagioclase feldspar and black pyroxene. The quarry is north of the town of Rustenburg.he orebodies within the complex include the UG2 (Upper Group 2) reef containing up to 43.5% chromite, and the platinum-bearing horizons Merensky Reef and Plat Reef. The Merensky Reef varies from 30 to 90 cm in thickness. It is a norite with extensive chromitite and sulfide layers or zones containing the ore.