"Mnizourin" is from Aramaic, mne (numbered) + tzorin (stones), the cholem deflected into the diphthong omicron upsilon in Greek. In Aramaic, the masculine plural ends with the letter nun instead of "mim" as in Hebrew. The text of the "Chaldean Oracles" as it comes to us can best be found appended in "The History of Philosophy" by Thomas Stanley, Esq. (1701). He relies upon 2 forms: the manuscript of Franciscus Patricius for the "Chaldean Oracles of Zoroaster" in Greek with a later Latin version, plus a commentary by the 11th Century Byzantine monk, Psellus. No mention of the stone exists in the main manuscript. We consider an earlier version to have existed based upon Psellus. Psellus speaks of the stone in Greek as "Mnizuris", but we know it as "Mnizourin" based upon Aramaic because the Oracles probably originated in Syria where Aramaic dominated. They possibly found their way to Rome through Eutropia of Syria then to Julianus (aka "Julian the Apostate" after whom the "Chaldean Oracles of Julianus" are named) in Constantinople through Eutropia's daughter, the wife of Constantine.
To understand the meaning of the stone of "numbered stones," we should consider the work of Denise Schmandt-Bessarat in Iraq in the 1970's. She had been given a pile of tokens and bullae (clay envelopes for tokens) that archaeologists didn't find interesting. But when she studied them, a new understanding of the origins of writing blossomed. These were early forms of receipts, all in clay that had hardened into stone. She determined that writing came about by counting before taking on the proportions of imagery as in Egyptian.
In light of this, we can ask what "accounts" we number in the Stone of "numbered stones." The most reasonable and meaningful idea I can connect is that they refer to the issues of unforgiveness by which we hold the debts of others, and that the Stone is of our own making. This, when applied to the inner alchemy of sacrifice of the stone Mnizourin, becomes a vehicle for release. So in the "Chaldean Oracles," Psellus states in his commentary in Stanley's translation:
"The Daemons that are near the Earth are by Nature lying, as being far off from the Divine knowledge, and filled with dark Matter. Now if you would have any true discourse from these, prepare an Altar, and Sacrifice the Stone Mnizuris: the Stone hath the power of evocating the other greater Daemon, who, invisibly approaching to the material Daemon, will pronounce the true solution of demands, which he transmits to the demandant. The Oracle joyneth the evocative Name with the Sacrificing of the Stone." (Stanley, Part XIX, p. 61.)
It makes sense that such a demonic presence would hang onto a person's unforgiveness as a means of further vexation and this alone should drive anyone to such an extreme discourse. But in sacrifice of the Stone, the one who does so enters a profound catharsis in which remembrance of the issue becomes wiped from memory, being purified thereby, and the greater Daemon must honor it by answering truthfully.