Question re. soapstone in welding

No. Talc is an amphibole mineral, as is asbestos. However talc is sufficiently different in crystal habit from asbestos that there's no risk.

There has been a case where low-grade talc used as a filler in children's wax crayons was found to contain minuscule traces of asbestos. However this was _low-grade_ talc - the very fact that made it poor quality mineral talc was the somewhat fibrous nature of it, and this also made it unsuitable for the high-grade powdered talc trade. Any mineral talc with a risk of asbestos just isn't going to be chose for use in baby powder.

There is of course the issue that _any_ fine powder isn't a good idea to be breathing in, asbestos fibres or not.