Looks like etch marks. I would charge $4,000 to $5,000.00 it's a pain in the butt job. If they don't like to price let someone else stand in that shower for 2-4 days and hold up an hand machine.
Thank you
Carl Staples
Classic Marble & Stone Restoration
610-356-4100
www.marblerestore.com
From: sccpartners@stoneandtilepros.simplelists.com <sccpartners@stoneandtilepros.simplelists.com> on behalf of Mike Alston <realmikealston@gmail.com> Sent: Thursday, June 7, 2018 9:33 PM To: sccpartners@stoneandtilepros.simplelists.com Subject: Mineral deposits
After scratching the wall and nothing came off I believe this is mineral deposits.