I found this. I don't know if a special GJ is different.
Prior to each Term of Court, the grand jury list is used to select the names of those citizens who will be summoned for service on the Grand Jury. This can be done either manually or by computer, depending on the county. In counties which rely on a manual system, the Commissioners take names from the Grand Jury list and place them on slips of paper which are put into the Grand Jury box. The box is brought into open court where a judge of Superior Court draws between 18 and 75 names of persons to be summoned for duty on the Grand Jury. In counties which use a mechanical or computerized jury selection system, prior to each Term, 18 to 75 names from the grand jury list are selected at random by the computer in accordance with local court rules
Then there is this.
While a trial jury must reach a unanimous vote to convict,
a grand jury only requires a majority vote of 12 or more to approve an indictment. Furthermore, only 16 of the 23 jurors have to be present. If they decide to approve the indictment, the words “true bill” will be endorsed on it.
www.georgiacriminallawyer.com
.
I feel better now.