Madagascar Garnets

Written by Alain Darbellay GGGems

Continued from page 1

right left Deltoid dodecahedron Pentagonal tetraedrical dodecahedron . Almandine in matrix Spessartite (Ambohimarangitra) Malaya (Andoharano) Malaya (Madagascar) Rhodolite (Ankilytokana) Hessonite (Soakibany) Imperial Malaya (Madagascar) In Madagascar, one finds rhodolite in a gneiss rich in biotite, in which (almandite-pyrope) is presented inrepparttar form of small grains, or withrepparttar 109301 state of large porphyroblasts, generally deprived of geometrical contours, plagioclase (oligoclase with andesine) isrepparttar 109302 feldspar dominating and sometimes exclusive. These gneisses contain sometimes pegmatic beds very rich in crystals. One very finds also garnetiferous gneisses containing little biotite, hardly directed. Kinzigites. The gneisses which have been just enumerated have a very clear schisteous structure, which had withrepparttar 109303 biotite abundance. A rather frequent type is approximately blocks and presents a compact aspect, thanks torepparttar 109304 prevalence of large garnets without geometrical form, associated quartz and feldspar granoblastic, biotite is not very abundant. The structure points out that of corneal micaceous of contact ofrepparttar 109305 granite. This gneiss can be compared withrepparttar 109306 kinzigite ofrepparttar 109307 Black Forest. Leptynites with amphibolo-pyroxenite intercalation rich in garnets of a pale pink (almandite-pyrope), with often rutile and graphite abound in certain areas of Madagascar. The feldspar is orthoclase, associated with ogigoclase-albite feldspar and sometimes with spindle-shaped microperthite, there exists much of myrmekite. These rocks are with fine grins, but they very often contain large regularly distributed crystals. Usually garnet does not have a geometrical form, but it takes clear faces in more quartzose zones. Leptynites derive fromrepparttar 109308 granites by disappearance ofrepparttar 109309 mica;repparttar 109310 garnetiferous mica schists constituterepparttar 109311 opposed pole in which biotite prevails, with progressive disappearance of feldspar. The Besafotra river carry outrepparttar 109312 spessartites on several kilometers from their source, doubtless a sodolitic pegmatite. A walk of 25 kilometers amongrepparttar 109313 mountains is necessary to reach this place. SPESSARTITE GARNET The tanety "grounds borderingrepparttar 109314 river," are also repparttar 109315 object ofrepparttar 109316 orange garnet's fever. Sifting in river. Initially,repparttar 109317 spessartite appeared inrepparttar 109318 Besafotra river, searched out here near to its source. Ankilytokana, one ofrepparttar 109319 fabulous rhodolite occurrences exploited in a leptynite vein on a sixteen meters depth. RHODOLITE GARNET Leptynites are primarily consisted in alkaline feldspars and quartz. When these rocks are not ribboned, and that is frequent, it is often difficult to decide if a sample, not seen in place, belongs to a leptynite or an aplite, it should be noticed that in Madagascar, these last contain microcline and not of orthoclase. In this area, one observes graphite spangles inrepparttar 109320 leptynites. Malaya garnet discovered into September 1998, in eluvium in a broken up leptynite. The modest depth ofrepparttar 109321 deposit did not require a significant work to extract it. This stone shows an exceptional capacity to restore repparttar 109322 light, thanks in particular to its high refractive index, especially under not very enlightened condition. Malaya Garnet Discovery Cutting Styles¦Characteristics¦ Crystalline Systems ¦ Madagascar Sapphire ¦ Corundum data ¦ Malaya Garnet ¦ Rhodolite Garnet ¦ Spessartite Garnet ¦ Hessonite Garnet ¦

Your guide to GGGems Allrepparttar 109323 pictures on this site have been shot by Alain Darbellay © 1987 - 2004 All rights reserved.

Madagascar gem safari

Written by Alain Darbellay GGGems

Continued from page 1

The far-south of Madagascar, semi-desert, does not present Polychromatic sapphires from Iankaroka discovered in 1990. any asphalt road yet, dust and trepidations arerepparttar daily lot of any traveller. Sunsets andrepparttar 109300 natural life of its inhabitants offer an appreciable compensation. Rubies from Ianavoha. (South of Madagascar.) Ruby from Andranomilitsy (Vohitany) Syenitic-nephelinic vein of rubies in Andranomilitsy. -------------------------------------------------- In Soamiakatra, rubies were sold with sunglasses. The Mayor of Soamiakatra in 1989, (East of Antsirabe.)

Rubies from Soamiakatra inrepparttar 109301 high plateaus.

Here, rubies are always found in alluvium.

MADAGASCAN CORUNDUMS ----------------------------------------------- BLUE SAPPHIRE NATURAL COLOR Sapphire from Analafady ( Ambondromifehy ) North. The alluvial deposit of Ambondromifehy is exploited since 1996. It is located in a Jurassic limestone, butrepparttar 109302 origin of sapphires is in alkaline basalts fromrepparttar 109303 close volcanic zone. Mahatsara ( Ambondromifehy) GGGEMS.COM

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