Old bottle with strange closure

This bottle is one my boss opened last night and brought into the winery today. We’re perplexed by the strange closure. It was under a complete capsul so it seems to have come from the winery like that. It’s from the appellation Savennières. His guess is late 60s early 70s. It has that very heavy and soft lead/tin capsule material. The wine itself is very oxidative and nutty but the texture is quite smooth. It seems atypical of the region to make oxidative wines like this but I’m no expert. Have any of you seen this closure type before?