All, I miswrote in my post about using 3M dust masks in my cutting of
malachite. What I am using are 3M 8210-C Respirator N95 Particulate
mask. I have always called them dust masks when they are not.
Instructions on the box are as follows. USE FOR: Solids such as those
from processing minerals, coal, iron ore, flour, and certain other
substances. Liquid or no-oil based particles from sprays that do not
also emit oil aerosols or vapors. DO NOT USE FOR: Lead based
paints, paint spray, oil aerosols, gases, vapors,asbestos, or
sandblasting. The respirator does not supply oxygen. These are not
cheap masks. They cost about $30 US for 20 masks which is about the
same as replacement filters for my rubber respirator. They work very
well for me.