Alternative Renderer for Texture override of the falling sand entity

Hello, i am making a mod that adds an new type of obsidian, obsidiand (I'm still working on the name) it's sand from obzidian and therefore it has gravity, so I let it extend BlockSand and I do the usual stuff and it works. But whenever it falls the texture changes to the equivaltent texture from terrain.png, after some searching I found the spot I have to edit: in RenderFallingSand.java is this line :

public void doRenderFallingSand(EntityFallingSand par1EntityFallingSand, double par2, double par4, double par6, float par8, float par9)
    {
        GL11.glPushMatrix();
        GL11.glTranslatef((float)par2, (float)par4, (float)par6);
        this.loadTexture("/terrain.png");
        Block var10 = Block.blocksList[par1EntityFallingSand.blockID];
        World var11 = par1EntityFallingSand.getWorld();
        GL11.glDisable(GL11.GL_LIGHTING);

        if (var10 == Block.dragonEgg)
        {
            this.renderBlocks.blockAccess = var11;
            Tessellator var12 = Tessellator.instance;
            var12.startDrawingQuads();
            var12.setTranslation((double)((float)(-MathHelper.floor_double(par1EntityFallingSand.posX)) - 0.5F), (double)((float)(-MathHelper.floor_double(par1EntityFallingSand.posY)) - 0.5F), (double)((float)(-MathHelper.floor_double(par1EntityFallingSand.posZ)) - 0.5F));
            this.renderBlocks.renderBlockByRenderType(var10, MathHelper.floor_double(par1EntityFallingSand.posX), MathHelper.floor_double(par1EntityFallingSand.posY), MathHelper.floor_double(par1EntityFallingSand.posZ));
            var12.setTranslation(0.0D, 0.0D, 0.0D);
            var12.draw();
        }
        else if (var10 != null)
        {
            this.renderBlocks.func_78588_a(var10, var11, MathHelper.floor_double(par1EntityFallingSand.posX), MathHelper.floor_double(par1EntityFallingSand.posY), MathHelper.floor_double(par1EntityFallingSand.posZ), par1EntityFallingSand.field_70285_b);
        }

        GL11.glEnable(GL11.GL_LIGHTING);
        GL11.glPopMatrix();
    }

so I thought I would just make an RenderFallingObsidiand wich extends RenderFallingSand and override the texture. But I can't find the place in the code where Minecraft decides which renderer to use.

I have been stuck with this for days and i can't find a solution.