On Saturday you can pick up a genuine Metro rock, buy a sack of Florida oranges, watch an authentic Chinese Lion Dance and get on the subway for a free ride through four new Arlington Metro stations.

These are among the many activities planned to celebrate the extension of the Orange Line in Arlington. Festivities vary at each of the four new stations -- Courthouse, Clarendon, Virginia Square and Ballston -- but free food, concerts, and dance demonstrations will be featured at each station from 10 a.m. to 4 p.m.

A day-long Florida orange sale sponsored by the arlington Lions Club will be held at the Virginia Square station. Metro rocks excavated during subway construction will be handed out at all stations.

The opening celebration kicks off at 8 a.m. with a five-mile run along the route of the subway tracks above ground. The race begins and ends at the Courthouse and runners must register there by 8:45 a.m.

Arlington's first official Christmas tree, located near the Ballston station, will be lit at noon. Decorations for the tree were made by students at Arlington's George Mason Special Education Center.

The official ribbon-cutting ceremony for the new stations is scheduled at 1 p.m. in Clarendon. Speakers include Gov. John N. Dalton, Metro General Manager Richard S. Page and a host of local officials.

The hour-long ceremony will be followed by a traditional Oriental lion dance and kung fu demonstration sponsored by the dozen Indochinese businesses located in Clarendon.

Free rides between the four stations are available between 8 a.m. and 4 p.m., but those who want to hop on a train and go downtown must pay regular fare. After 4 p.m. passengers getting on or off at any new statin will pay 50 cents.

Arlington officials say they expect as many as 5,000 people to attend the day-long celebration. For additioal information on events call 558-2291.