'This "powdery" mineral is number 1 on the Mohs scale of hardness'
talc
GEOLOGY: This powdery mineral is number 1 on the Mohs scale of hardness
This "powdery" mineral is number 1 on the Mohs scale of hardness
This "powdery" mineral is number 1 on the Mohs scale of hardness
GEOLOGY
talc
GEOLOGY