July 7 (Reuters) - Black Rock Mining Ltd BKT.AX
* provides update on recent legislative changes passed by tanzanian parliament
* Co has received legal advice confirming that it is too early to ascertain full impact on co's mahenge graphite project
* Co refrains from providing commentary on impact that changes will have on its mahenge graphite project Source text for Eikon: ID:nASXbh3rmD Further company coverage: BKT.AX