Porous Rocks and the All-New Nether Furnace

Want:  
Three new blocks — Gray Porous Rock, White Porous Rock, Nether Rubble — a cave biome (Porous Caverns) for the first two, and a Nether Furnace made from Nether Rubble.

Why:  
Andesite, diorite, granite have been "useless stones" for years. These rocks give every stone a job and add dozens of textures from just three new blocks. Blast furnace (ores) and smoker (food) are fast, but misc recipes (sand to glass, cactus to dye) still wait at a slow furnace.

How — rocks:  
Each porous rock has 30 fill points. Right-click a stone block: all 30 used and it becomes a two-texture mix. Right-click ore: 1 point each, 5 per face, studded on the surface; 30 fills it. A comparator reads it: 2 points = 1 signal — a stone block hits 15; 30 ores too. Nothing is consumed. Gray/White hold water; Nether Rubble holds lava (never both). Survival reversible; adventure locked (puzzle maps). Sneak + right-click fills blocked faces. Pistons drop the ores. Silk Touch carries block and contents.

How — furnace:  
4 Nether Rubble = 4 bricks; 8 bricks in a ring = the Nether Furnace. It smelts only non-ore, non-food items (sand to glass, cactus to dye, clay to brick) at double speed. Nether Rubble also burns as fuel (about two logs) and becomes Gray Porous Rock when done.

Feasibility:  
Reuses Chiseled Bookshelf logic and old netherrack textures. About 20 stone types x 3 rocks = roughly 60 texture combos from three new blocks.