This mod is part of The Vanilla Experience.
Nether portals spread nether blocks to the overworld around the portal in a configurable radius.
The mod transforms Dirt, Grass and Stone, to Netherrack, Quartz Ore and Nether Brick, and transforms Sand and Gravel to Soul Sand.
portalSpreadRadius (default = 15, min 1, max 100): The radius around the portal to which the nether blocks can spread.
spreadDelay (default = 2500, min 20, max 360000): The delay in ms in between the spread around the nether portal.
instantConvertAmount (default = 50, min 0, max 1000): The amount of blocks that are instantly converted to a nether block around a portal when it is detected. If there are existing nether blocks within the radius, their count is substracted from this number.
coalPreventsSpread (default = true): When enabled, blocks the spread effect when there are two coal blocks within the radius.
isQuartzChance (default = 0.05, min 0, max 1.0): The chance the next spreaded block is quartz ore.
isNetherBrickChance (default = 0.2, min 0, max 1.0): The chance after the quartz roll that the next spreaded block is netherbrick.
You can stop the spread effect by placing two coal blocks within the radius of the nether portal:
In this case they are placed in front of the portal, but they can be placed anywhere as long as it's within the radius.