Learning CenterWhat is a mineral?The most common minerals on earthInformation for EducatorsMindat ArticlesThe ElementsThe Rock H. Currier Digital LibraryGeologic Time
搜索矿物的性质搜索矿物的化学Advanced Locality Search随意显示任何一 种矿物Random Locality使用minID搜索邻近产地Search Articles搜索词汇表更多搜索选项
╳Discussions
💬 Home🔎 Search📅 LatestGroups
EducationOpen discussion area.Fakes & FraudsOpen discussion area.Field CollectingOpen discussion area.FossilsOpen discussion area.Gems and GemologyOpen discussion area.GeneralOpen discussion area.How to ContributeOpen discussion area.Identity HelpOpen discussion area.Improving Mindat.orgOpen discussion area.LocalitiesOpen discussion area.Lost and Stolen SpecimensOpen discussion area.MarketplaceOpen discussion area.MeteoritesOpen discussion area.Mindat ProductsOpen discussion area.Mineral ExchangesOpen discussion area.Mineral PhotographyOpen discussion area.Mineral ShowsOpen discussion area.Mineralogical ClassificationOpen discussion area.Mineralogy CourseOpen discussion area.MineralsOpen discussion area.Minerals and MuseumsOpen discussion area.PhotosOpen discussion area.Techniques for CollectorsOpen discussion area.The Rock H. Currier Digital LibraryOpen discussion area.UV MineralsOpen discussion area.Recent Images in Discussions
Identity HelpLocality of columbite from Madagascar - Analalava vs. Tsaramanga
12th Jul 2012 01:25 UTCPavel Kartashov Manager
But locality http://www.mindat.org/loc-157722.html don't contain any pagmatite minerals but only mineralized basaltic effusive rocks.
Fromother hand, here was uploaded photo very similar crystal - http://www.mindat.org/photo-149304.html
Other very similar crystals we see in classic pegmatite occurrence http://www.mindat.org/loc-27803.html
Compare my specimen with http://www.mindat.org/gallery.php?loc=27803&min=1112
I am confused...:-(:-S:-(
By the way my mineral in reality is Sc-bearing ferroan and titanoan Manganocolumbite. It contains inclusions of quartz, microcline, films of bastnasite-(La), pseudomorphoses of bismuthite after bismuthinite and overgrown by minute tetragonal prismes similar to xenotime.
12th Jul 2012 09:09 UTCKnut Edvard Larsen 🌟 Manager
The geology of the Analalava District consist, as you say, only of cretaceous basaltic roks and jurassique-cretaceous and tertiary sedimentary layers. The columbites like these come from precambrian granite pegmatites (55o MA) from the socle of the Madagascar highland. There are so far as I know no granite pegmatites in the Analalava district,. and none marked on the geological maps of the area.
There is a granite pegmatite field with Beryl-Columbite subtype LCT pegmatites in the neighbour District of Analalava, in the Bealanana District , along the River Meavarano wich produced some columbite in the 1950s, but I have not seen these.
Your sample looks indeed very similar to samples from Tsaramanga. I have several in my collection, collected at the Tsaramanga pegmatite. Together with these I found also bismutite pseudomorphs after bismuthinite etc.
But , of course i can't say with a 100% certainty that your specimen is from Tsaramanga. It may come from another locality- but not Analalava District.
12th Jul 2012 09:54 UTCKnut Edvard Larsen 🌟 Manager
10th Jan 2015 02:20 UTCPavel Kartashov Manager
版权所有© mindat.org1993年至2024年,除了规定的地方。 Mindat.org全赖于全球数千个以上成员和支持者们的参与。
隐私政策 - 条款和条款细则 - 联络我们 - Report a bug/vulnerability Current server date and time: 2024.4.26 23:44:16
隐私政策 - 条款和条款细则 - 联络我们 - Report a bug/vulnerability Current server date and time: 2024.4.26 23:44:16