Blue gold

local BGLD = elem.allocate("LBPHACKER", "BGLD")        -- * Allocate element ID.
elem.element(BGLD, elem.element(elem.DEFAULT_PT_GOLD)) -- * Base it off GOLD.
elem.property(BGLD, "Name", "BGLD")                    -- * Name it BGLD in the menu.
elem.property(BGLD, "Color", 0x238AD6)                 -- * Give it a bluish colour.
elem.property(BGLD, "HighTemperatureTransition", 1500) -- * Make it a bit more difficult to melt.
elem.property(BGLD, "Graphics", function(i, r, g, b)   -- * A lot like GOLD's graphics function.
    return 0, ren.PMODE_FLAT, 255,
        r + math.random(-5, 4),
        g + math.random(-5, 4),
        b + math.random(-5, 4)
end)

elem.property(elem.DEFAULT_PT_LAVA, "Update", function(i, x, y, ...)

    -- * If this particle is molten IRON...
    if sim.partProperty(i, "ctype") == elem.DEFAULT_PT_IRON then

        -- * ... then look for molten GOLD neighbours...
        local gold_neighbours = {}
        for ny = y - 1, y + 1 do
            for nx = x - 1, x + 1 do
                local id = sim.partID(nx, ny)
                if id
                and sim.partProperty(id,  "type") == elem.DEFAULT_PT_LAVA
                and sim.partProperty(id, "ctype") == elem.DEFAULT_PT_GOLD
                and math.random(1, 100) <= 70 then -- * Accept this neighbour with a 70% chance.
                    gold_neighbours[#gold_neighbours + 1] = id
                end
            end
        end

        -- * If there are at least three such neighbours...
        if #gold_neighbours >= 3 then

            -- * ... then turn turn all of them and this particle into BGLD.
            sim.partProperty(gold_neighbours[1], "ctype", BGLD)
            sim.partProperty(gold_neighbours[2], "ctype", BGLD)
            sim.partProperty(gold_neighbours[3], "ctype", BGLD)
            sim.partProperty(i                 , "ctype", BGLD)
        end
    end
end)