The International Mineralogical Association's approved amphibole nomenclature has been revised in order to simplify it, make it more consistent with divisions generally at 50%, define prefixes and modifiers more precisely and include new amphibole species discovered and named since 1978, when the previous scheme was approved. The same reference axes form the basis of the new scheme and most names are little changed but compound species names like tremolitic hornblende (now magnesiohornblende) are abolished and also crossite (now glaucophane or ferroglaucophane or magnesioriebeckite or riebeckite), tirodite (now manganocummingtonite) and dannemorite (now manganogrunerite). The 50% rule has been broken only to retain tremolite and actinolite as in the 1978 scheme so the sodic calcic amphibole range has therefore been expanded. Alkali amphiboles are now sodic amphiboles. The use of hyphens is defined. New amphibole names approved since 1978 include nyböite, leakeite, kornite, ungarettiite, sadanagaite and cannilloite. All abandoned names are listed. The formulae and source of the amphibole end member names are listed and procedures outlined to calculate Fe3+ and Fe2+ when not determined by analysis.

The International Mineralogical Association's approved amphibole nomenclature has been revised in order to simplify it, make it more consistent with divisions generally at 50%, define prefixes and modifiers more precisely, and include new species of amphibole discovered and named since 1978, when the previous scheme was approved. The same reference axes form the basis of the new scheme, and most names are little changed, but compound species names like tremolitic hornblende (now magnesiohornblende) are abolished, as are crossite (now glaucophane or ferroglaucophane or magnesioriebeckite or riebeckite), tirodite (now manganocummingtonite) and dannemorite (now manganogrunerite). The 50% rule has been broken only to retain tremolite and actinolite as in the 1978 scheme; the sodic-calcic amphibole range has therefore been expanded. Alkali amphiboles are now sodic amphiboles. The use of hyphens is defined. New amphibole names approved since 1978 include nyböite, leakeite, kornite, ungarettiite, sadanagaite and cannilloite. All abandoned names are listed. The formulae and source of the amphibole end-member names are listed, and procedures outlined to calculate Fe 3+ and Fe 2+ where not determined by analysis.

Summary Lamprophyres are ‘alkaline rocks’ because they carry high alkalis at a given percentage of SiO 2 , together with one or more of normative ne, lc or ac , modal foids, and Na-K-Ti-rich amphiboles or pyroxenes. They reach higher whole-rock H 2 O, CO 2 , Sr and Ba contents than other silicate igneous rocks. Contents of related element subsets in amphiboles (Ti, Ba), K-feldspars (Ba, Fe 3 ), phlogopites (Ti, Ba, Fe 3 ) and pyroxenes (Ti, Al, Fe 3 ) include among the highest values known in nature for these minerals. ‘Primitive’ minerals (diopside, forsterite) commonly coexist with ‘evolved’ minerals (albite + orthoclase, quartz). Four well-defined ‘branches’ of the lamprophyre ‘clan’ have distinctive compositions: calc-alkaline (shoshonitic) lamprophyres (minettes etc.), alone among lamprophyres, have mixed alkaline-calc-alkaline affinities; alkaline lamprophyres (camptonites etc.) are basanitic to nephelinitic and, alone among lamprophyres, usually have Na < K; ultramafic lamprophyres (alnöites etc.) are the most Si poor and Ca rich of silicate igneous rocks, and grade into carbonatites; lamproites (orendites etc.) are uniquely rich in K, Rb, Ba, Th, Mg, Cr and Ni at mainly ‘andesitic’ SiO 2 contents, and carry a suite of diagnostic minerals (wadeite etc.). Each branch comprises at least four rock types which resemble each other much more than rock types of other branches; however, some rock types can be grouped into slightly distinct ‘families’ within one branch (e.g. phlogopitic and madupitic lamproites). A case can be made for including kimberlites as a fifth branch of the lamprophyre clan. Synoptic plots and tables, based on some 5000 major, trace-element and mineral analyses, are presented, to aid identification and classification. Lamprophyres are far more common than generally stated, occurring worldwide in more tectonic settings than many other alkaline rocks and throughout the geological record. They may approximate intratelluric magma compositions. Nearly all represent primitive magmas, and many represent primary magmas. Some represent parental magmas to a wide range of hydrous alkaline intrusive suites: calc-alkaline lamprophyres to potassic pyroxenite-diorite-shonkinite-syenite-granite plutons (Cortlandt); alkaline lamprophyres to hornblendic gabbro-syenite plutons (Monteregian Hills); and ultramafic lamprophyres to ijolite-carbonatite complexes (Fen).

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Calc-alkaline lamprophyres are porphyritic dyke-rocks, richer in amphibole, biotite, ultramark elements (Mg, Cr, Ni) and incompatible elements (K, F, P, Rb, Sr, Zn, Nb, Ba, REE, Th, U) than other rocks of comparable colour index (35–67) or % SiO2(46–57). Field and petrological criteria are suggested for identifying them uniquely. New average compositions, based on some 600 screened analyses, confirm the chemical variability but possible heteromorphism of vogesites, kersantites, spessartites and some minettes. Calc-alkaline lamprophyres probably crystallise from volatile-rich, crystal-laden fluids. Microdioritic ‘porphyrites’, K-rich syenites and quartz-feldspar porphyries commonly form from these fluids by acidic hybridisation, and more rarely byin situdifferentiation. Calc-alkaline lamprophyres have close compositional equivalents among, for example, shonkinites and absarokites, but not among kimberlites or common plutonie or volcanic rocks. They are compositionally more ‘crustal’ than lamproites and leucitites, despite some overlap. They are far more widespread than other K-rich or alkaline rocks. Three genetic petrological associations are confirmed: with calc-alkaline granitoid plutons (A), with shoshonitic volcanic and subvolcanic suites (B), and with appinite—breccia-pipe complexes (C). Most calc-alkaline lamprophyres, from association A, perhaps form by crustal modification of primary lamproitic or leucititic magmas; a very few, carrying rare mantle-type xenoliths, may represent relatively unmodified, but otherwise similar, primary magmas. Those of association B may form merely by volatile enrichment of shoshonitic magmas during subvolcanic crystallisation. Different origins for minettes in these associations are suggested by compositional differences, revealed by discriminant analysis.