Typically blasting agents.
What are the least sensitive explosives used by military
c4
c4
Several of the plastic explosives based on RDX, such as Composition C4 are relatively insensitive. And there are specialized explosives developed for use in deep oil well bores that stand up well to very high temperatures and pressures. However, at normal temperatures and pressures, the LEAST sensitive group of products are probably blasting agents, such as a mix of ammonium nitrate and #2 diesel fuel. Unless compacted, these will not reliably detonate from a blasting cap, and require a high explosive "booster" to donate enough energy to cause detonation.
Composition C-4. It consists of RDX in a plasticizer, and takes significant shock to detonate.
Arch magazine
Several of the plastic explosives based on RDX, such as Composition C4 are relatively insensitive. And there are specialized explosives developed for use in deep oil well bores that stand up well to very high temperatures and pressures. However, at normal temperatures and pressures, the LEAST sensitive group of products are probably blasting agents, such as a mix of ammonium nitrate and #2 diesel fuel. Unless compacted, these will not reliably detonate from a blasting cap, and require a high explosive "booster" to donate enough energy to cause detonation.
Probably ammonium Nitrate charges used for engineering tasks such as cratering. Those charges cannot be reliably detonated by a blasting cap alone, but require the use of a booster explosive to make them shoot.
forearm
While we use several, you are probably thinking of Composition C4. It is composed of RDX explosive in a mix of a plastic binder. In Great Britain it is called PE-4. It is a low sensitivity explosive with high energy.
You will be least sensitive to pressure originating from the proprioceptors in your joints and muscles. These receptors are responsible for detecting body position and movement, and are not as sensitive to external pressure compared to touch receptors in the skin.
You need at least a Nightmare Pickaxe before you can mine the Ebonstone, but you can use explosives to break it.