One Pound Isle Of Man 1978 Silver? Virenium? Platinum?

Weigh it. 

What is your actual question ?? It was minted in all three metals 

From the color alone I would say non of the above 😅, silver, copper-nickel and platinum usually are colorless (metallic grey).

Edit: Looking up the make-up of that strange trademarked alloy, they seem to use way more copper then I thought. So maybe it will have a red hue.

The circulation piece was in virenium 

It must be virenium - this one: N#6873

I see two letters as die mark, probably BB (so it will be Virenium Proof), silver and gold ones have only one die mark letter.

My uncirculated 1978 virenium coin looks distinctly yellowish - like aluminum-bronze or brass.

 Same as in the link in the reply above yours - 

those original pictures look to have been taken indoors at night.