Great question - and a complicated one, so we're glad you asked! First off, you should know that “all-natural” product claims can be vey misleading because there’s no official government organization that endorses the term, much less pinpoints a specific definition for it. Translation: it’s most likely pure marketing.
That being said, there are third parties (like ECOCERT, for example) that offer a special “all-natural” certification that you may have seen on other products. You’re probably wondering how these types of organizations define the phrase in these instances, and here’s how… They claim that it means no single ingredient in the product itself was made in a lab. And when it comes to using mineral sunscreen actives like zinc oxide and titanium dioxide, they are always - contrary to popular belief - produced synthetically in a lab. This is to ensure that the materials do not contain any impurities or traces of hazardous materials.
So this means that there truly is no such thing as an all-natural sunscreen, whether its actives are mineral or chemical. And, as with most things, something that's made in a lab isn't necessarily "bad"- especially SPF!