the netherite isn't burns in the lava but isn't float in the lava

the netherite isn't jump in the lava

What I expected to happen 

i trow a netherite in the lava and float

What actually happened was...:
trow a netherite in the lava and isn't float

Steps to Reproduce:
1. i get a netherite
2. and i trowed in the lava 
3. ...