This is called stone money, or Rai, it's most common on Palau.
Rai, or stone money (Yapese: raay), are large, circular stone disks carved out of limestone formed from aragonite and calcite crystals. Rai stones were quarried on several of the Micronesian islands, mainly Palau, but briefly on Guam as well, and transported for use as money to the island of Yap.
People don't carry stone money around with them, instead the community is aware of who owns which stone. These stones are typically used for major transactions, such as the purchase of land or a ship, political deals, ransoms, inheritance, or something noteworthy. The specific value of the stone does not have a quantifiable dollar figure (despite the US dollar being a common trade unit for smaller transactions in areas such as Guam where the stones are used), instead the value of the stone is purely qualitative, linked to the craftsmanship of the item, the prestige of the various people in the stone's lineage of ownership and the numerous anecdotes that build up the stone's story.
The stronger the story, the more power the stone has... that alone makes it a great form of currency to sit in the background of a FUBAR story. The mechanisms of play already reflect this concept.
I'm thinking that these stones make the perfect crypto-currency in a cyberpunk tax-haven setting. You can't tax these transactions, because you can't chip away at these stones. The value is specifically off the books, but hugely culturally significant. I could easily imagine an increased value through trades of these stones, to the point where entire companies are traded in exchange for a rock that never physically moves. The chamber of commerce and master bankers of the region would be a coven of tribal elders who might spend their days fishing, hunting, weaving, or doing other decidedly non-technological things. These elders wouldn't have to do live their lives in such a way, they would each be worth billions of dollars. Corporate CEOs would
Mercenaries would be hired to deface (or even destroy) the stones, and counter-operatives would lie in the jungle to prevent any such attacks from occurring. Failed attempts to destroy or deface a stone might improve it's anecdotal worth (or might improve the value of all tones if the specific target remained unidentified). Successful attempts to destroy or deface a stone might send global stock markets into chaos.
Meanwhile the elders live out their lives, maybe they know the true power these stones have over the world. Maybe they don't.