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Nephrite specimens from Longxi,Sichuan,prepared by ion-thinning and dispersion techniqueshave been studied using TEM and SAED.A series of sub-microscopic textures such as (010) multi-ple-chain faults and related fault terminations,(001) mechanical twinning,sub-grain boundaries orfault walls,tremolite fibrous pseudoform of talc and intergrowth of tremolite and talc with (010) asinterface are revealed.By analogy of metallographic textures,characteristics and mechanisms of theprocess of“deformation-recovery-recrystallization”are discussed in detail,Topotactic reactionmechanism by which tremolite retrogresses to talc was studied and a retrogressive metamorphic originof Longxi nephrite is proposed.
Nephrite specimens from Longxi, Sichuan, prepared by ion-thinning and dispersion techniques have been studied using TEM and SAED. A series of sub-microscopic textures such as (010) multi-ple-chain faults and related fault terminations, (001) mechanical twinning , sub-grain boundaries orfault walls, tremolite fibrous pseudoform of talc and intergrowth of tremolite and talc with (010) asinterface are revealed. By analogy of metallographic textures, characteristics and mechanisms of the process of “deformation-recovery-recrystallization” are discussed in detail Topotactic reaction mechanism by which tremolite retrogresses to talc was studied and a retrogressive metamorphic origin of Longxi nephrite is proposed.