The real life substance with almost the same chemical formula as kryptonite is called?

In November 2006, researchers working for global mining corporation Rio Tinto Group discovered a mineral they could not identify. They sought the aid of Dr. Chris Stanley (a mineralogist working at the Natural History Museum in London) along with Dr. Pamela Whitfield and Dr. Yvon Le Page (researchers from Canada’s National Research Council) and found they had discovered… Kryptonite. Well almost.

In fact it was Jadarite, a white, earthy monoclinic silicate mineral, whose chemical formula is: LiNaSiB3O7(OH) or Na2OLi2O(SiO2)2(B2O3)3H2O. Jadarite's chemical formula is very, very close to the formula ("sodium lithium boron silicate hydroxide with fluorine") invented for the fictional substance kryptonite in the 2006 film Superman Returns. This coincidence attracted mass-media attention, and jadarite was covered by ABC, BBC, CNN.

All the other three substances mentioned are genuine and, like Jadarite, can be checked on Wikipedia.