Why are Halides so scarce?
Halides are a class of mineral that contains a Halogen atom (non-metal elements in Group 17) and another, electropositive atom. Halides form in nature where sediments occur, often in shale. Because of their non-metal nature and high solubility, halides are often destroyed by pressure and heat, both processes which create rock and metallic ore; the most commonly-occurring halide is Rock Salt (NaCl), or Sodium Chloride. The Chlorine atom is the Halogen, while the Sodium atom is the electropositive atom; while they form a chemical compound, they are susceptible to alteration with natural events. Water interacting with halides tends to dissolve its chemical structure, while intense heat breaks the halide apart into its component elemental atoms.
igneous rocks cool from molten lava so water based minerals can't survive
metamorphic rocks has so much heat and pressure that it would destoyed halides
sedimentary its possible because they are where halides can form (near water) tho Carbonates are still more common
Silicate minerals are the most common (answer gotten from Yahoo Answers.com)