Below stone density is about 2.6 and hardness is 7 . The color is purple and dark grey.
Your SG and Hardness is right on the button for Chalsedony and my impression from your photos is that some of your specimens are petrified wood.
Very thanks .
Could be Amethyst in Quartz.
I would have to agree with petrified wood
Amethyst is quartz.