I've made a living material that slowly spreads by replacing other materials with itself, but now I need a way to stop its spread. If needed I can add information about the material. Thanks!

If it's biological: fire, cold, acid, disease. If it's more like replicants: fire, acid, lightning.

I'm more looking for a material such as a metal or other mineral.

To make it easier I will give you the description of the material:

The material that I made is [GLASS]

• [GLASS] is a living material that has an appearance similar to that of different shades of red or, extremely rarely, black glass. Occasionally it will pulsate with a red light
• [GLASS] is extremely sharp, being able to easily slice through solid steel and strong, being able to withstand the force of small explosions without receiving damage. In addition, it has been found to be impervious to cold, fire, lightning, poison and radiant damage.
• 1 ft. x 1 ft. x 1 ft. of [GLASS] weighs approximately 900 lbs
• [GLASS] attempts to corrupt non-living materials to turn them into itself, allowing it to slowly spread throughout the land. Creatures that die while in contact with this substance are slowly claimed by it, turning them into [GLASS] Reincarnations, crudely recreated versions of the original creature made of [GLASS] and is hostile to trespassers.
• [GLASS] can be somewhat detected by the slight sense of foreboding it gives off. This effect is better observed when approaching or while inside of a [GLASS] biome

Ah so something more like (hypothetical) Neutronium with extreme density and cohesion. Make it only manipulable by graviturgy or raw force magic or something alike.

My 2ct: your Glass material seems a bit too overpowered/invincible to me - if it isn't gonna be for some inevitable "end of times" scenario.

Since it seems to be one single entity, all you need is for one point of contact with a similarly reactive material that eats it faster than it eats other stuff and it will spread through the whole thing. You could also have some kind of energy that pulses through it to turn it to sand or something. I would say radiant, but it seems you've already ruled that out.

I would say water, and anything currently wet.

so lakes, rivers, mud, swamp, living things, plants, etc. all incorruptable - unless there's a drought!

Deserts would be likely already [GLASS] as they are so dry.

Also gives concern for the planet as the [GLASS] might spread un the stone underneath things like Bogs, in places where the water hasn't made it.

You could give [GLASS] a weakness to water, making it much less sturdy. 

Another option (which could be a plothook thing) would be a creature, insect, or plant which uses the Shatter spell to feed on [GLASS]. Shatter would be my default approach to dealing with [GLASS]!