 | | 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 | | 8 Front cover: A Spessartite garnet in mica, Madagascar (Sorbonne collection) 0.08 inch. B Tourmaline...rhodochrosite. 10 Amazonstone and smoky quartz, Lake George, Park Co., Colorado (Coil family- Richard...26-27 Opal .................... . 106-107 Amethyst quartz ............. 100-101-102-103 Hyalin...oriental emerald, oriental topaz and oriental amethyst. Some rubies and sapphires have a remarkable feature...of those rocks. Spine! is frequently found in Madagascar, Ceylon, Australia and Burma. A Spine/, Burma |  | | Catalog/List | | pure greenish-yellow mass, no matrix Lake Alaotra, Madagascar lxl £5 Ix2£12. pure pale green crystal...a good lxl box£4 colour. Pieces in a box rich amethyst like masses in matrix. Large Hall Minc,Tonopah...Waldsassen, Oberpfalz,Germany. Maize, Antsirabe, Madagascar ½ x½£3 Ix½ £5 St Hilaire,Quebec,Canada Tel...KT! I 2NL Boron, Kem County,Califomia U.S.A Madagascar Ix! £2 lxl £7. S0 lxl £3.50 lx2 £4 ½x½ £4...lx2 £8 Mt Yukspor,Khibiny Massif,Kola,Russia Madagascar ½£4 I x½ £6 lx2 £1.50 2x2 £3 St Louis Claim |  | | Report (issue) | | The Natural History Museum of Milan and its Madagascar Collection The Museo Civico di Storia Naturale... the museum began paleontologic fieldwork in Madagascar (upper Permian fauna and Jurassic and Cretaceous...fieldwork in Madagascar in 1996 in collaboration with other institu tions in Madagascar, Italy, and the...Pezzotta has spent a total of twenty nine months in Madagascar making geological-mineralogical surveys. In collaboration...both classic and new minerals and gemstones from Madagascar opened at the Natural History Museum in Milan |  | | Book | | before our very eyes, as a result of deposits in sea, lake and river water, often under the influence of biological... Carbon Diamond Silica Quartz and its varieties Opal Amethyst Common or rare Minerals from pegma tites or metamorphic...radioactivity (smoky quartz), violet by manganese (amethyst), or may lose its transparency altogether and...Precious opal (Walangula, Australia): 10 cm. 3 - Amethyst (Guerrero, Mexico): 5 cm. W! •S'- ■ atw -;...with a diameter of between one and two feet. In Madagascar, the extraction of a single beryl crystal left |  | | Journal (issue) | | and star garnet cat's-eyes from Ambatondrazaka, Madagascar Dr Karl Schmetzer 1 , Dr Heinz-Jürgen Bernhardt...properties of star garnets from Ambatondrazaka, Madagascar, are given. All samples examined are intermediate...garnets have been offered in local markets in Madagascar since about 1997. The rough materials for these...of Ambatondrazaka which is located south of Lake Alaotra, about 160 km north-east of the capital Antananarivo...habit of garnet crystals from Ambatondrazaka, Madagascar, showing only the dodecahedron crystal form {110}: |  | | Catalog/List | | Laumontite from Mull, Tremolite crystals from Madagascar Moldavite.New stock of Chaoite.Talc from Egypt...FLUORESCENT Large brown well formed dodecahedral Madagascar 1 ins £4 ALMANDINE 1 Crystal I inch across garnet...group____________ Attractive green with white perthitic Madagascar AMAZONITE 60 2x3inch £5 Feldspar________________...(Carbonate Fluorapatite) Brown veins and Francois Lake, British Columbia masses m Andesite .Collected personally...Canada Terminated single brownish -grey crystal "'Madagascar' good form, sizes refer to height Greenish in |  | | Catalog/List | | · 868 BISMUTITE Damaraland Namibia 68 APATITE Madagascar Rich yellow mass on matrix with minor CUPRITE...BISMUTOTANTALITE Gamba Hill Uganda 33 APATITE Francois Lake, British Columbia, Canada pure brown cleavage (Carbonate...Cove,Arkansas,USA 579 CO BALTITE Near Elizabeth Lake, 5 miles cast of Espanola,Or Black single crystal...Morbihan, Brinany, France 920 COLLINSITE Francois Lake, British Columbia, Canada Light brown vein with...· 108 COQUIMBITE Alcaparossa Chile 86 CALCITE Madagascar Good sharp dark grey rhombic cleavages Pure mauve |  | | Catalog/List | | SITE Benallt Mine, Llcyn Wales . . 68 APATITE Madagascar Rich brown mass with approx 5 % Cymrite .Also...!:.m £~--- -·· · ·- _ ___ AuTe+Ag 86 CALCITE Madagascar Good sharp dark grey rhombic cleavages lx2£2..._ _ _ _ _F_e_Cr_o_ __ 85 CHRYSOBERYL Lake Alaotra Madagascar Yellow- green small crystal group . !~m-...feldspar. lxl £5 lx2 £8 83 CHRYSOBERYL Lake Alaotra, Madagascar 563 CERULEITE _ Whcal Maid incline of...to3 mm size crystal on and in Clinohumite. rich amethyst like masses in matrix. 1cm £3.60 lxl £5.60 Mg |  | | Catalog/List | | New East Wheal Russell mine, Devon ,Eng land Madagascar ½ x½ £2.50 lins£4 I x½ £4 )x i £6 Fall owfield...Arizona £2 Attractive green with white perthitic Madagascar 2x3 in ch inlergrowth. Cut and polished £5 Pu...Variety FRANCOLITE rich white cellular mass £1.20 Madagascar Terminated single brownish -grey crystal I inch... Holm bush Mine, Kelly Bray , Cornwall Francois Lake, Bri tish Columbi a Canada Holm bush Mine Cornwall...matrix Lake Alaotra, Madagascar !xi £5 lx2 £12 Yellow- green small crystal group Lake Alaotra Madagascar |  | | Catalog/List | | Feldspar lx2 £4 2x2 £8 1119 AXINITE 768 APATITE Madagascar Terminated single brownish -grey crystal good...__________________ Bo_s_o_14_ _ __ 33 APATITE Francois Lake, British Columbia, Canada (Carbonate Fluorapatite)...CHABAZITE . Ramsley Mine, Devon England B6 CALCITE Madagascar Good coverage of white masses with micros on...Beryl BcAIO lxl £4 lx2 £8 CHRYSOBERYL Lake Alaotra Madagascar Yellow- green small crystal group 1cm £6...£6 7mm £4 BcAIO CHRYSOBERYL Lake Alaotra, Madagascar pure greenish-yellow mass, no matrix lxl£S lx2£12 |  | | Catalog/List | | Palabora Mine, Phalabora, Transvaal, South Afri, Madagascar 29 68 Tem1inated single brownish -grey crystal...x 2 £9 APATITE BARYTES Babbacombc Devon Francois Lake, British Columbia , Canada 33 1 1 27 (Carbonate...slivery mass on quartz Bi S 8mm £5 ■■ CALCITE Madagascar 86 Good sharp dark grey rhombic cleavages l x2...Feldspar lxl £4 lx2 £8 CELSIAN CHRYSOBERYL Lake Alaotra, Madagascar Benallt Mine, Lleyn, Wales 995 83 pure...lxl £5 ½ ins £3 CERUSSITE CHRYSOBERYL Lake Alaotra Madagascar 726 Arenas Mine, Oridda . Iglesias, Sardinia |  | | Catalog/List | | ALMANDINE Large brown well fom1ed dodecahedral Madagascar I ins£4 garnet group Crystal I inch across ALSTONITE...__ County. _ AI1zona 60 AMAZO:-;ITE 2x3i nch£5 Madagascar Anractive green with white penhitic _Feldsp�ar...£4 - Tcrmina1ed single brownish -grey crystal Madagascar 1 . 5 inch APATITE £6 Ca PO/4/ F -- - -- -good...CALCITE Good sharp dark grey rhombic cleavages Madagascar 504 BUSTAJ\I ITE Mn- -Ca -SiO -- - -- - ·-76...matrix Kcmi Finland 1 29 CHRO!\IITE Fe Cr O Lake Alaotra Madagascar Yellow- green small crystal group 85 CHR |  | | Catalog/List | | fibrous mass (once known as PICROLITE) lxl £5 Francois Lake, British Columbia , Canada 33 APATITE (Carbonate...EMATITE I x I £6 I x2 £ I 2 Feldspar 2x2 £ 30 Madagascar DARYTE APATITE TalTs Well, near CurdilT Walcs...x'I, £3 l x2 £ 1 .50 Cu Fe S l x l 80p Blackstone Lake, Parry Sound, Ontario, Canada 2 1 1 IIASTNAESITE...P0/4 CI PyTOxcne Fe Ct O Page 4 b Lake Alaotra Madagascar CHRYSOBE RYL Ycllow- g n:c:n small crystal...£ 6 701111 £4 Do AI O 83 CIIRYSOBE RYL Lake Alaolra. Madagascar pure greenish-yellow m ass, no matrix |  | | Journal (issue) | | been found in China, Egypt, the Italian Alps, Madagascar and Mexico. Agate has also been found in parts...garnet are found in Australia, Brazil, India, Madagascar, Sri Lanka and Tanzania. The largest crystals...main amazonite deposits exist today are: Canada, Madagascar, Mexico, Namibia, Russia, Tanzania and Zimbabwe...E S AM C --1 THE DISTINCTIVE COLORATION OF AMETHYST IS m GENERALLY BELIEVED TO BE CAUSED BY THE...THE --1 PRESENCE OF IRON OXIDE :::c -< Cl) Amethyst is typically a rich purple or violet colour. It |  | | Book | | 127 Hiddenite 84 67 127 Heliotrope 83 Amethyst Gahnite Heliodor 78 Collophane 60 126 Hawk’s-Eye...pictured: vi In the opening of part 1, the amethyst seal of the Roman emperor Titus, who, imitating...Garland, J. Amster of the Compagnie Générale de Madagascar, J. Sirakian of the Taillerie de Royat, and S...Roman emperor Titus, who reigned from a.0. 79-81. Amethyst intaglio. Height: 1.37 cm. M. De Bry collection...Chibcha of South America offered gold and emeralds to Lake Titicaca (see EMERALD). Tribal chiefs, priests, |  | | Journal (issue) | | District (AZ), Goldschmidt $12 v.21/#3 American Amethyst Localities, Terlingua, Davis Hill, Edgarbaileyite...Idria mines (Yugoslavia), Outlaw Seriphos (Greece), Lake George Eugui quarries (Spain) $12 mine (NV), Pribram... v.20/#3 Ouro Preto (Brazil), Anjanabonoina (Madagascar), $12 Port Radium Silver (Canada) $12 v.25/#1...goshenite beryl, zinnwaldite, smoky quartz and amethyst, plus the finest specimens known of a new tourmaline-group...this chapter. What is called “almost colorless amethyst like” from the Bolshaya Tyazhelovesniy mine would |  | | Journal (issue) | | Johne FGA, L Joyner PhD FGA, H Kitawaki FGA CGJ, R J Lake FGA DGA, Li Li Ping PhD FGA DGA, M A Medniuk FGA...colour change behaviour have also been found in Madagascar (M.S. Krzemnicki, pers. comm., 2004). 6 Garnet...non-basalt-related deposits in the Isalo area of Madagascar, from Ratnapura, Sri Lanka and from Mogok, Myanmar...non-basalt-related origin (e.g. from Sri Lanka, Myanmar or Madagascar) is now straightforward. However, distinction...as between Thailand and Australia, or between Madagascar, Sri Lanka and Myanmar – are much more difficult |  | | Book | | as a protection against drunkenness - the name amethyst in fact means 'not drunken'. Clear transparent...hydrothermal products are agate amygdales with amethyst, calcite, and other minerals in basalts; minerals...freshwater deposits of iron, known as bog iron ore and lake iron ore. Salt deposits are characteristic examples...Elongated prismatic crysffiis (cp. Fig. 19, p. 133). Madagascar. Formation and occurrence. Two types of deposit...the Black Quartz: 2 - Coiored varieties Above Amethyst, part of a geode. Uruguay. Center Massive rose |  | | Book | | have been uncovered in the region of Great Bear Lake in northwest Canada, on the Colorado Plateau, in...United States, the sabi "range" at the for head of Lake Superior, is Megood only another generation or...and veins of Arizona. Sapphire, moss agate, and amethyst are typical of Montana. The list is apparently...The helicopter has a tremendous future tle Doctor Lake, Northwest Territories. in the search for minerals...prospector and Canada have numerous pegma- in Madagascar, South Africa, Sweden, and Norway also have a |  | | Book (edition) | | virtually indistinguishable from natural citrine and amethyst, which are now produced in Russia and Japan on...geode containing amethyst from volcanic rocks in Rio Grande do Sul, Brazil. The amethyst crystals are more...magma of its host rock. Both the fire opal and the amethyst have formed from hydrothermal fluids (see p. 27)...the vein deposits of amethyst, emerald and tanzanite. Gem minerals such as amethyst, aquamarine, morganite...such as chrome tourmaline and chrome diopside. Amethyst occurs in many localities worldwide but some of |  | | Journal (issue) | | Euclase from Brazil Inclusions in Demantoid from Madagascar Photochromism Part 2 Volume 38 / No. 1 /...Demantoid Garnet from Antetezambato, Northern Madagascar—Internal Characteristics and Their Use in Deciphering... Štubňa Gem Notes Aquamarine from Manakana, Madagascar | Star Augite from Vietnam | Crocoite from Tasmania...COLOURED STONES Aquamarine from Manakana, Madagascar Madagascar is well known as a source of aquamarine...pegmatitic districts on the west side of Lake Alaotra in central Madagascar. In this case, the specific aquamarine |  | | Book (edition) | | resulting in interesting overgrowths as shown in the amethyst quartz example in Figure 22. Because the overgrowth...Parallel growth of many smaller amethyst crystals upon larger amethyst crystals. Group of smoky purple...GROWTH 91 Opening 7 Soe Chalcedony b ands AMETHYST GEODE Faces on tips As Largest crystals line...lower part of Figure 45. Similar cross-sections of amethyst display alternating purple and colorless segments...polarized light. Sharp sectors mark twins. Right: amethyst cross section. Brazil twins marked by violet and |  | | Journal (issue) | | had to go on. GEMS & GEMOLOGY WINTER 2019 Madagascar are from metamorphic deposits, but the deposits...basalts—two very different deposits, yet both from Madagascar. As stated earlier, when geographic origin determination...ring, courtesy of Ronald Ringsrud; a 7.04 ct Madagascar sapphire, courtesy of Mayer & Watt; and an exceptional...such as in Sri Lanka (Ratnapura, Elahera) and Madagascar (Ilakaka), produce the highest-quality sapphires...(Sumjam), Myanmar, Sri Lanka (figure 1), and Madagascar. Sri Lanka is so far the most important producer |  | | Book (edition) | | Chalcedony (moss agate). Parallel Growths Quartz (amethyst), calcite, fiuorite , galena. C RYSTA L I NCLUSIONS...Parallel growth of many smaller amethyst crystals upon larger amethyst crystals. Group of smoky purple...solutions, rapid and imperfect gro,vth is likely to Lake place on all cry tal faces. 1\ s noted on previous...often broken or CRYSTAL GROWTH 91 Opening AMETHYST GEODE Faces on tips of crystal1/ Largest crys...formation sho,vs drusy layers, AMETHYST- A.......,_._;:, -1 SPHALERITE-AMETHYST CHALCE DONYAMETHYST - =--~ |
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Lake Alaotra, Alaotra-Mangoro, Madagascar