Treat the men well and the ore will come.
This translation did not make a lot of sense to me, So I tried to look into it myself:
大切にする means to cherish or to treasure.
I knew 石 as “stone”, but it also mean gem (a precious stone).
So, “If you treasure people, gems will appear”.
If I had to find a similar proverb, it would go like:
“Who finds a friend finds a treasure”.
@mike-lima
The author of the English-Japanese pair is not probably a native speaker either in Japanese or English. I noticed that this person posted a lot of unnatural sentences on Tatoeba…
The English sentence is not a proverb, but a sentence made by this person. Read the comments on Tatoeba. I recommend you to just push the “ignore” button and move on.
We don’t say 石 in the context of “precious gem”. It’s actually quite opposite.
玉石混淆（ぎょくせきこんこう）is a good example. 玉石混淆 illustrates the situation where great and low qualities of something are chaotically mixed – e.g. Twitter上のコメントは玉石混淆だ (some posts on Twitter are worth reading, but some are awful.)
玉 means a “precious stone” or “gem” whereas 石 is an “ordinary (worthless) stone”, a “kidney stone” or even an “ordeal/hardship”.