 | | Journal (article/letter/editorial) | | June 29, 2016 REV. R. BARON ON THE GEOLOGY OF :MADAGASCAR. 305 18. N o ~ s on the GrozooY 0fM*DXGASCAR...] [PLATESXIII. & XIV.] GE~-ERAL DESCRIPTION. MADAGASCAR is as yet almost a terra incognita to the geologist...of this great island. The central portion of Madagascar is generally regarded as consisting chiefly of...by far the greater part of the eastern half of Madagascar consists of gneiss and other crystalline rocks...of the island ~. Hence the roads from Central Madagascar to the east run over an endless series of more |  | | Book | | DE MADAGASCAR ET DÉPENDANCES GÉNÉRAL GOUVERNEMENT LES PIERRES A par PRÉCIEUSES MADAGASCAR M. ...Trimestre 1906) LES PIERRES à PRÉCIEUSES Madagascar PIERRES PRÉCIEUSES LES Etat actuel de la...année. vient de A MADAGASCAR pierres précieuses remplir dans à Madagascar la Colonie Cette mission...de Fianarantsoa jusqu’à la mont Vohimirafy (district de nous documenter sur la limite nord de la...ses dérivés, les granulites, les pegmatites, les quartz de pegmatites sont abondants. Des éruptions récentes |  | | Book (volume) | | figurent pas dans ceux-ci. En ce qui concerne Madagascar, d’où documents nouveaux, offrant un intérêt...coloration brun rouge. GISEMENTS ET ASSOCIATIONS Madagascar. — J’ai donné le nom d’ampaugabéite [C. B. CXLIV...ANrHOPHYLLITE-GÉDRITE (ï. p. 035; 1 , T. VI, p. 784). — Madagascar. J’ai rencontré [B. S.M. XXXV. 97. 1912) un...micaschistes mont Bitv). IV, p. 787). — Madagascar. J’ai visité le gisement d’Ambatoarina, d’où...rappelant certaines crocidolites. On y voit associés du quartz, de la pyrite, de l’albite et parfois des mouches |  | | Report (issue) | | ••• ••• ... ... • •• French \Vest Africa Madagascar • •• • • •• 96 • •• ••• • •• 97 ••• ...stone. In other stones~ such as some varieties of quartz ar1d chrysoberyl, the tubes a-1~e parallel to one...topaz,'' '' Spanish topaz '' and '' quartz topaz '' are yellow quartz (.citrin-e) ; '' Brazilian sapphire...abundant n1ine1..als on the face of the ea.r th, quartz .in one form or another is often tised for jewellery...ornaments, but is to•o common to be of high value. 'rhe quartz gen1stones fall iI1to two main varieties, th,ose |  | | Book (volume) | | Sunstone, : : Amazonstone . : 5 : Moon. 1d4 Quartz: Crystals and Cut Stones of Rock Crystal, Citrines...information on a number of topics, particularly on the quartz gems. Mr. J. Asscher, Jnr., of Amsterdam checked...is composed mainly of feldspar, glassy-looking quartz (rock crystal) and mica, which are essential minerals...than quartz so that the feldspar crystals are more likely to show external form than the quartz (Figure...Alluvial SS > + f ee me + + + + placers River Quartz sand i Arenaceous grains i U ioe |MEXSCERIS |  | | Book (volume) | | Bulletin de le la. Muséum en particulier Madagascar, ai joint le Comptes Société française de...leur surface est parfois recouverte de cristaux de quartz et de petits cristaux de barjtine et de fluorine...fluorine. La romanéchite a pour gangue le quartz et la fluorine violette ou elle cimente fréquemment des sortes...par des cristaux de mômes minéraux servent de quartz, de fluorine, de barytine, etc. Ces gangue à la...des minéraux qu’elle accompagne elle pseudomordu quartz, parfois avec de la romanéchite on la voit phisée |  | | Book | | example is very rare indeed compared to salt or quartz, but not compared to ruby, the particular conditions...of it crystallizes as free silica in the form of quartz, as in a granite. Along with the increasing silica...crystals (resembling bamboo stalks) in some emerald, quartz and garnet • anatase in rock crystal • apatite...fuchsite in quartz, emerald and corundum pyrite in corundum and emerald rutile in quartz spinel in ruby...diamond. Pegmatite minerals such as apatite and quartz may be found in another pegmatitic mineral, aquamarine | | | Book | | example is very rare indeed compared to salt or quartz, but not compared to ruby, the particular conditions...of it crystallizes as free silica in the form of quartz, as in a granite. Along with the increasing silica...crystals (resembling bamboo stalks) in some emerald, quartz and garnet • anatase in rock crystal • apatite...fuchsite in quartz, emerald and corundum pyrite in corundum and emerald rutile in quartz spinel in ruby...diamond. Pegmatite minerals such as apatite and quartz may be found in another pegmatitic mineral, aquamarine |
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