What is "ruby of zinc"

Ruby \Ru"by\, n.; pl. Rubies. [F. rubis (cf. Pr. robi), LL. rubinus, robinus, fr. L. rubeus red, reddish, akin to ruber. See Rouge, red.]

1. (Min.) A precious stone of a carmine red color, sometimes verging to violet, or intermediate between carmine and hyacinth red. It is a red crystallized variety of corundum.

   Note: Besides the true or Oriental ruby above defined, there are the balas ruby, or ruby spinel, a red variety of spinel, and the rock ruby, a red variety of garnet.

   Of rubies, sapphires, and pearles white.
   --Chaucer.

2. The color of a ruby; carmine red; a red tint.

   The natural ruby of your cheeks.
   --Shak.

3. That which has the color of the ruby, as red wine. Hence, a red blain or carbuncle.

4. (Print.) See Agate, n., 2. [Eng.]

5. (Zo["o]l.) Any species of South American humming birds of the genus Clytol[ae]ma. The males have a ruby-colored throat or breast.

   Ruby of arsenic, Ruby of sulphur (Chem.), a glassy substance of a red color and a variable composition, but always consisting chiefly of the disulphide of arsenic; -- called also ruby sulphur.

   Ruby of zinc (Min.), zinc sulphide; the mineral zinc blende or sphalerite.

   Ruby silver (Min.), red silver. See under Red.