Really sorry that happened to you. I will see what can be done to make it clearer that Quartz does not spawn in the Magma layer. I did try adding that hint to the Nix unlocking clue as well but it ended up making the prompt a bit too lengthy.
For now, the hint is included in the rotating "Did You Know?" section under the Play button and on the game page, but it sounds like it is still easy to miss. Thanks for reporting this and for the feedback!