Pegmatit

Pegmatit (az yun. regmatos —mustahkam vaslshuda), jinsi fishondai beshtar kalondonaest, ki dar bayni jinshoi kuhi dar shakli rag, dayka, linza va digar jismho joygir shudaast. Tuli in jismho ba chandin km va gafsiashon ba chandsad m merasad. Pegmatit dar marhilai okhirini tashakkuli massivhoi intruzivi kristall mebandad. Mineralhoi asosii Pegmatit az mineralhoi magmai asli firhe nadorand. Odatan tarkibi mineralii Pegmatit Nifont boy buda, makhsusan dar baynn onho mineralhoe, ki moddahoi tez bukhorshavanda (ob, ftor, bor, khlor va gayra) dorand, khele bisyorand. Dar baze Pegmatitho ba miqdori ziyod payvasti elementhoi nodir va poshkhurda (Li, RB, Ss, Ve, Nb, Ta, Zg, Hf, U, 8c va gayra) yoft meshavand. Odatan kristallhoi mineralhoi Pegmatit az devorai raghoi pegmatiti to ba miyonahoi on toraft kalon shuda meravand. Andozan baze kristallho 1—2 m³ ast.

Paydoishi Pegmatitho bo jinshoi intruzivii tursh (granitu granodioritho), ishqori (sienitho va sienithoi nefelindor), asosi (gabbro), ultra-asosi (peridotitho) vobasta ast. Pegmatiti graniti az hama beshtar pahn shudaast. Tamomi khelhoi Pegmatit ba gayr az mineralhoi asosii jinsofarii boz ba miqdori gunogun turmalin, muskovit, berill, flogopit, spodumen, mineralhoi metallhoi nodir va payvasthoi Nb, Ta, R, U, Th va gayra dorand. Roje ba paydoishi Pegmatit aqidahoi gunogun hast. Pegmatitho doroi ohamiyati kaloni amaliand. Onho baroi sanoati kuloli va shisha manbai shpathoi dashti, baroi sanoati radio va elektrotekhnika manbai abraqu pezokvarts buda, hamchunin koni sanghoi qimatbaho ba shumor meravand. Pegmatithoi graniti koni metallhoi nodir va mineralhoi nodirzamin (spodumen, berill, kolumbit, tantalit, lepidolit, kassiterit, pollutsit, uranu toriy va gayra) meboshand. Dar Tojikiston Pegmatitho dar qatorkuhhoi Qurama, Turkiston, Hisoru Oloy va kuhhoi Pomir vomekhurand. Dar SSSR khususan Pegmatithoi Kareliya, Ukraina va Ural mamuland.

Ad.: Fersman A. E., Pegmatiti, 3 izd., t. G, M.—L., 1940; Pegmapiti, Sb., L.,- 1972.