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Rediscovery of manandonite in the Sahatany Valley, Madagascar
| Content Provider | Semantic Scholar |
|---|---|
| Author | Ranorosoa, Nadine Fontan, François Fransolet, André-Mathieu |
| Copyright Year | 1989 |
| Abstract | Manandonite oeeurs as white f1akes with a pearly lustre on the micaceous (001) cleavage, associated with elbaite and quartz lining vugs of saccharoidal albite, collected in the type locality, i.e. the Antandrokomby pegmatite. Optieally pseudo-uniaxial to biaxial positive (2V about 10-15°). a = ß = 1.604(5). The erystals are often twinned on (001) as 6-fold seetors. Manandonite is a 1:1 layer silicate (7 A serpentine-kaolinite group) and ean be eonsidered as a two-layer polytype with a C-eentred orthorhombie-shaped cell (a = 5.057, b = 8.765, C = 13.769 A, spaee group C2221). The strongest X-ray lines are 6.92 (100)(002), 4.362 (25)(110), 3.447 (80)(004), 2.489 (15)(131,201), 2.376 A (35)(132,202). A wet-ehemical analysis gave Si02 23.02, B203 7.71, Al203 47.85, Fe203 0.36, MnO 0.02, MgO 0.03, CaO 0.07, Na20 0.13, Li20 5.38, H20 15.40, sum 99.97 wt.%, whieh yields the ideal formula, LizAI4[(Si2AIB)OIO](OH)s, with Z = 2. Dmeas. = 2.78(2); Deale. = 2.79. The thermal behaviour and the infrared speetrum constitute additional features to differentiate manandonite from cookeite. Key-words : manandonite, lithium, boron, serpentine-kaolinite group, Madagasear. |
| Starting Page | 633 |
| Ending Page | 638 |
| Page Count | 6 |
| File Format | PDF HTM / HTML |
| DOI | 10.1127/ejm/1/5/0633 |
| Volume Number | 1 |
| Alternate Webpage(s) | http://content2.schweizerbart.de//download/xyJjHFtuFevntde97cv2giZJ8kELGK |
| Alternate Webpage(s) | https://doi.org/10.1127/ejm%2F1%2F5%2F0633 |
| Language | English |
| Access Restriction | Open |
| Content Type | Text |
| Resource Type | Article |
