guessing game

Guess the element found in the formation of this ?

It is also present it fertilizers.

(starts with P)

Guess the element present in Atomic clocks?

It is found in minerals like pollucite and lepidolite

Guess the soft metal belongs to f-block,

which is used in infrared lasers, laser surgery, eye-safe laser etc.

Guess the element which have these properties - non-corroding high-melting-point hard metal, densest element, electric contacts, pen tips, needles, fingerprint powder

I smell like rotten eggs, and I’ve been accused of ruining parties. Guess my formula?