Kryptonite

Kryptonite was a chemical element listed on the Periodic Table of Elements. It was a member of the Hypersonic series. 

It was a transuranian substance that was found naturally under its crystalline form. There were several varieties of kryptonite, classified by color. There were two major sources of kryptonite in the galaxy: Kevratas and a planet on the border of the Lyran Star Empire called Krypton. There were several kryptonite varieties, black, red, green, orange, blue, white and pink being discovered before the RIS surveyed Krypton for kryptonite deposits. All variants known as of 2385 were radioactive.


 * As the events of Sphere of Influence seem to depict kryptonite as it is in Superman, Sphere of Influence thus implies that the Hypersonic series were the elements in the island of stability in the continuity.

Effects of kryptonite
Red kryptonite was known to be potentially harmful to Romulans, while green kryptonite was able to strip a Betazoid of any telepathic powers while exposed to it.

The short-term effects of yellow kryptonite on Romulans could be alleviated by drinking raktajino. Handling of yellow kryptonite required an EV suit.