Like @Archenassa here, I have always enjoyed the Diamond Mine mode found in other match-3 games.
One would think that a mining style mini-game would fit well with the theme of Khaziel with a reward scheme along the lines of Treasure Hunt (i.e. the deeper you reach, the better chances for good rewards).
To save adding additional in-game currencies, perhaps Treasure Maps could also count as Mining Claims, allowing players to choose their mini-game of choice for single-player rewards.
Treasure maps that actually lead to buried treasure that you have to dig up yourself! 
I am so 100 % behind this! 
For those who don’t know what the Diamond Mine is, here’s a page explaining it all. It is awesome. Enough said. All of my support! 
Mmmm. I second that idea as well. The more, the merrier ! 
That would totally work 
Personally I was thinking about something similar, but instead of digging at the bottom we would digging into layers of the background.
And just like the treasure map has it’s own “gems” I would love to see shovel, pickaxes, tnt etc for this game.
@Stix Actually they have a mode like that in which you have a limited amount of time to unearth artifacts from sand; it’s a mini-game that is kind of fun and is called Sandstorm. Might be closer to what you had in mind. I could not find a satisfying screenshot, and I haven’t reinstalled the game since I upgraded my OS so I can’t take one for you. 
Edit: typo.
I can’t stress enough how much I prefer limited moves over limited time.
I googled the sandstorm mode, and it does have some resemblance to what I had in mind.
Friendly neighborhood +1 necrobump =)
this would be a good one to reward with “stones” since you are digging
I was thinking Gems 