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ash tuff lapillistone and lapilli tuff original

broader	pyroclastic rock original
definition	Pyroclastic rock in which less than 25 percent of rock by volume are more than 64 mm in longest diameter. Includes tuff, lapilli tuff, and lapillistone.

basalt original

broader	basic igneous rock original fine grained igneous rock original
definition	Fine-grained or porphyritic igneous rock with less than 20 percent quartz, and less than 10 percent feldspathoid minerals, in which the ratio of plagioclase to total feldspar is greater 0.65. Typically composed of calcic plagioclase and clinopyroxene; phenocrysts typically include one or more of calcic plagioclase, clinopyroxene, orthopyroxene, and olivine. Includes rocks defined modally in QAPF fields 9 and 10 or chemically in TAS field B as basalt. Basalt and andesite are distinguished chemically based on silica content, with basalt defined to contain less than 52 weight percent silica. If chemical data are not available, the color index is used to distinguish the categories, with basalt defined to contain greater than 35 percent mafic minerals by volume or greater than 40 percent mafic minerals by weight.
narrower	alkali olivine basalt original tholeiitic basalt original

basanite original

broader	tephritoid original
definition	Tephritoid that has a plagioclase to total feldspar ratio greater than 0.9, and contains more than 10 percent normative (CIPW) olivine.

basanitic foidite original

broader	foiditoid original
definition	Foiditoid that contains less than 90 percent feldspathoid minerals in the QAPF fraction, and has a plagioclase to total feldspar ratio that is greater than 0.5, with greater than 10 percent normative olivine.

basic igneous material original

broader	igneous material original
definition	Igneous material with between 45 and 52 percent SiO2.
narrower	basic igneous rock original

basic igneous rock original

broader	basic igneous material original igneous rock original
definition	Igneous rock with between 45 and 52 percent SiO2.
narrower	basalt original gabbroic rock original

bauxite original

broader	material formed in surficial environment original
definition	Highly aluminous material containing abundant aluminium hydroxides (gibbsite, less commonly boehmite, diaspore) and aluminium-substituted iron oxides or hydroxides and generally minor or negligible kaolin minerals; may contain up to 20 percent quartz. commonly has a pisolitic or nodular texture, and may be cemented.

biogenic sediment original

broader	sediment original
definition	Sediment composed of greater than 50 percent material of biogenic origin. Because the biogenic material may be skeletal remains that are not organic, all biogenic sediment is not necessarily organic-rich.
narrower	ooze original organic rich sediment original

biogenic silica sedimentary rock original

broader	non clastic siliceous sedimentary rock original
definition	Sedimentary rock that consists of at least 50 percent silicate mineral material, deposited directly by biological processes at the depositional surface, or in particles formed by biological processes within the basin of deposition.

bituminous coal original

broader	coal / kohle original
definition	Coal that has vitrinite mean random reflectance greater than 0.6% and less than 2.0% (determined in conformance with ISO 7404-5), or has a gross calorific value greater than 24 MJ/kg (determined in conformance with ISO 1928). Hard, black, organic rich sedimentary rock; contains less than 91 percent fixed carbon on a dry, mineral-matter-free basis, and greater than 13-14 percent volatiles (dry, ash free). Formed from the compaction or induration of variously altered plant remains similar to those of peaty deposits.