no visible porosity
71Crater Lake National Park — IUCN Category II (National Park) …
72STS-31 — Infobox Space mission mission name = STS 31 insignia = Sts31 flight insignia.png shuttle = Discovery launch pad = 39B launch = April 24, 1990, 8:33:51 a.m. EDT landing = April 29, 1990, 6:49:57 a.m. PDT duration = 5/01:16:6 altitude = 330… …
73Morchella — Morel redirects here. For other uses, see Morel (disambiguation). Morel A black morel in Poland Scientific classification Kingdo …
74Sterling silver — is an alloy of silver containing 92.5% pure silver and 7.5% other metals, usually copper. The sterling silver standard has a minimum millesimal fineness of 925. Fine silver (99.9% pure) is generally too soft for producing large functional… …
75Pneumothorax — Classification and external resources Right sided spontaneous pneumothorax (left in the image). An arrow indicating the edge of the collapsed lung. ICD 10 J …
76Lassen Peak — and Devastated Area from Cinder Cone Elevation 10,462 ft (3,189 m) …
77Concretion — For other uses, see enterolith and nodule (geology). Septaria redirects here. For the genus of gastropods, see Septaria (gastropod). Concretions on Bowling Ball Beach (Mendocino County, California) weather out of steeply tilted Cenozoic mudstone… …
78Arc welding — uses a welding power supply to create an electric arc between an electrode and the base material to melt the metals at the welding point. They can use either direct (DC) or alternating (AC) current, and consumable or non consumable electrodes.… …
79Pozzolana — Pozzolana, also known as pozzolanic ash, is a fine, sandy volcanic ash, originally discovered and dug in Italy at Pozzuoli in the region around Vesuvius, but later at a number of other sites. Vitruvius speaks of four types of pozzolana: black,… …
80Natural American Spirit — is a brand of cigarette and tobacco products manufactured in the United States by the Santa Fe Natural Tobacco Company, a wholly owned independent subsidiary of Reynolds American, in turn 42% owned by British American Tobacco. The company was… …
