Yes, that's a good approach. I violated some of my own rather loose guidelines with this investment. One accidentally, and the other by choice.
The one I violated by choice is "invest in a company where you understand the product, the market and the business model". I understand minerals exploration, geology, and extractive mining. I don't understand potassium salt mining, production or marketing.
The one I violated by accident is "if I'm going to invest in a startup, pick one that has begun transitioning to commercial operation". I was seduced by the value proposition in the global potassium fertiliser market, and the material announcements coming from the company. And because I had made the above choice I didn't have the ability to recognise the risks. I am grateful to @sevo for the constant nitpicking and clearly argued words of caution with numbers, calculations, logical inferences, and examples. It is almost purely down to this poster that I was cautious and didn't increase my investment above my initial stake.
SO4 Price at posting:
31.0¢ Sentiment: None Disclosure: Held