You don't use one on the Purple Monolith. Use the rover's winch as you did with the meteorite, to pull the surface rocks away.
you keep buying flowers atil the you get the shovel
After you chase her to the Rock lab, you can't find her again. When you use the Geiger Counter to find the Purple Artifact, she catches up to you.
There is no electric saw on Lunar Colony. To enter the Infirmary at the Research Lab, climb to the top and use the pressure chamber to temporarily squash you down, then quickly slip past the boxes that are blocking the door. The exit from the Infirmary is in the maintenance area.
To enter the Rock lab, you need a keycard (dropped by Salerno when you find her) and purple eyes that you can get from the machine in the Research Lab.
The only Lunar Island I know of is the one on the MMORPG, Runescape. You can find it in the north-west part of the games world map.
The green stone is not the one you are trying to find. The green, orange, and pink artifacts do not do anything early in the quest. You are looking for the 4th one, which is purple. (see the related question)
There is a winch attached to the rear of the lunar rover, and you will use it twice. Click on the hook and carry it to where it is needed. The winch is NOT used with the Geiger Counter (delicate equipment) -- push over one of the steel beams to act as a ramp to the rover.
When you find Salerno at the BioDome, she escapes through the airlock, and drops her keycard. If you have already turned your eye color to purple to beat the retina scan, you can follow her into the Rock lab.
Go down and across to the right, then up to reach the storage room, where you will find the geiger counter. Push the tall beams over and you will have a ramp to load it onto the rover.
On Mercay island you go deep into the tunnle and as you keep going you'll find a room with a treasure chest and a book. The shovel will be in the chest.
The Purple Artifact is just south of the Rock Lab, but you can only find it when you are using the Geiger Counter. You will see a purple light and a crack in the ground. Use the rover hook to pull away the rocks on top.
The colony was Rhode Island. He and many of the Massachusetts settlers were apparently not content with the laws there.