When you break the red sandstone slab, It's take long time to destroyed with pickaxe. But, It's doesn't set hardness like normal red sandstone
Environment
OS : Windows XP (x86) 5.1 Service Pack 3
CPU : Intel(R) Pentium(R) 4 CPU 2.80GHz
RAM : 1 GB DDR RAM
Java : Java Development Kit 1.7.0 Update 67 (Use for making mod)
Graphic Card : Intel 845G 512 MB
OpenGL Version : 1.3.0 - Build 4.14.10.4342
Not exactly sure what you mean, but probably a duplicate of MC-53641