[ANSWERED] Math.random is affecting all bricks with the same script?

I made a script so that with random numbers generated, the block (an ore) changes materials and such. But they all wind up exactly the same. If one block was selected as "Copper", the rest are coppers.

Can anyone help me fix the script without having to change the variable m=math.random

math.randomseed(tick())

local m=math.random(1,1000)

if m > 0 and m < 400 then
    script.Parent.BrickColor=BrickColor.new("Dirt brown")
    script.Parent.Material="Concrete"
    script.Parent.BlockValue="Dirt"
end

if m > 400 and m < 600 then
    script.Parent.BrickColor=BrickColor.new("Rust")
    script.Parent.Material="Ice"
    script.Parent.BlockValue="Copper"
end

if m > 600 and m < 750 then
    script.Parent.BrickColor=BrickColor.new("Institutional white")
    script.Parent.Material="Ice"
    script.Parent.BlockValue="Silver"
end

if m > 750 and m < 900 then
    script.Parent.BrickColor=BrickColor.new("CGA brown")
    script.Parent.Material="Slate"
    script.Parent.BlockValue="Iron"
end

if m > 900 and m < 950 then
    script.Parent.BrickColor=BrickColor.new("New Yeller")
    script.Parent.Material="Ice"
    script.Parent.BlockValue="Gold"
end

if m > 950 and m < 975 then
    script.Parent.BrickColor=BrickColor.new("Pastel Blue")
    script.Parent.Material="Ice"
    script.Parent.BlockValue="Diamond"
end

if m > 975 and m < 985 then
    script.Parent.BrickColor=BrickColor.new("Eggplant")
    script.Parent.Material="Granite"
    script.Parent.BlockValue="Obsidian"
end

if m > 985 and m < 990 then
    t=Instance.new("PointLight")
    script.Parent.BrickColor=BrickColor.new("Really red")
    script.Parent.Material="Cobblestone"
    script.Parent.BlockValue="Adurite"
    t.Parent=script.Parent
    t.Brightness=5
    t.Color=Color3.new(255,0,0)
    t.Range=10
end

if m > 990 and m < 995 then
    a=Instance.new("PointLight")
    script.Parent.BrickColor=BrickColor.new("Forest green")
    script.Parent.Material="Pebble"
    script.Parent.BlockValue="Viridian"
    a.Parent=script.Parent
    a.Brightness=5
    a.Color=Color3.new(85,170,0)
    a.Range=10
end

if m > 995 and m < 999 then
    g=Instance.new("PointLight")
    h=Instance.new("Fire")
    script.Parent.BrickColor=BrickColor.new("Dark blue")
    script.Parent.Material="Foil"
    script.Parent.BlockValue="Bluesteel"
    g.Parent=script.Parent
    g.Brightness=5
    g.Color=Color3.new(0,0,255)
    g.Range=10
    h.Parent=script.Parent
    h.Heat=3
    h.Color=Color3.new(0,0,255)
    h.SecondaryColor=Color3.new(0,0,255)
    h.Size=13
end

if m > 999 and m < 1001 then
    k=Instance.new("Sparkles")
    script.Parent.BrickColor=BrickColor.new("Black")
    script.Parent.Material="Cobblestone"
    script.Parent.BlockValue="Black Iron"
    k.Color=Color3.new(85,0,255)
end