Marcus Jordan Drug Possession Charge Changed to Ketamine

The white substance cops found in Marcus Jordan's pocket during his DUI arrest was determined to be ketamine -- NOT cocaine -- TMZ Sports has learned.

Cops conducted a field test on the powder during 34-year-old Jordan's Feb. 4 traffic stop ... and while initial testing resulted in a positive reading for cocaine, the Florida Department of Law Enforcement also did further tests, which concluded it was actually ketamine.

Considering the two substances feature the same color and texture, ketamine can often yield a positive cocaine reading ... so it isn't out of the ordinary, we're told.

For those keeping score at home, Jordan's updated charges are now possession of ketamine, DUI with property damage, and resisting arrest.

The State Attorney's office made sure to switch the drug designation ... but other than that, it all remains the same with the original charge.

It could actually benefit Jordan ... as cocaine is a Schedule II drug, and ketamine is Schedule III in Florida.

Days after the arrest, Jordan entered a not guilty plea in the case.

Jordan's been mostly tight-lipped over the run-in with cops ... only thanking those who reached out to him in the days following the arrest.