What is tianzhu, the mineral?

A good question. I was led to believe that Tianzhu was merely a
description (in Chinese, it means heaven) and I've seen it used to to
refer to all sorts of things from beads to bamboo chopsticks.

If anyone else can shed light on this, I too would be interested.

I haven't found any reference to Tianzhu as a mineral. 

- Tianzhu is a name of an area (both a mountain area China and a name
of Northern India).

_ Tianzhu (Huang) is a type of bamboo , called in English Bamboo
Secretion (Bambusa textilis).

I am not sure where you saw this word, but could it be that the
jewelry was made in Tianzhu?

I think I found the solution. The instance I ran into, the word
"tianzhu" was in quotation marks. It defined the material of some
antique Chinese objects offered by an internet vendor in Shanghai. I
surmise he is using a computer software program to translate Chinese
into English. I think he erred in trying to input the symbols that
translate into "zhen yu", the word for jade.
I just happened to click on a button he had left behind in 1 item &
viewed the the entire text in Chinese.

Plausible?

Please provide the Chinese character for "Tianzhu". In chinese, there
are a lot of word that pronounce similarly but it can mean different
things.

Thanks.

Sorry, the item I mentioned is no longer on site. I would not have
known which particular character applied anyway.