I had a jar of that too but seem to remember it being labeled 1.8 microns.
I threw it away when it dried up

Its a liquid now
I just dug into the back of the compound drawer to see what was left...
I think the 1.8 micron stuff was 'Black Diamond.' At least that what my jars say. Don't have any of the Boron left though I seem to remember it, but the Black Diamond is 1 full jar and 3/4 of the other jar still full after 15 years of use. Stuff goes a looong way.
I've also got a couple of new jars and some almost full jars of 2.5 mic silicon carbide and 6 mic silicon carbide, also from back in the day. Those jars are a paste form, a bit softer than the bars but not soft enough to squish when I press my thumb into them. The one full and one half full bottles of liquid CrO2 (both about 8oz bottles) are about as thick as whipping cream. Green whipping cream. I guess I must have bought every type of compound HA was selling, as well as a lot of compounds from other retailers in my quest for the perfect setup. Theirrs-Issard, Dovo, Reichmann, DMT, and a host of others that are now sitting in the drawers.
At the time I bought them, Keith was recommending using them on some of his leathers, so I bought 2-3 of each of the various leathers he sold too. About 6-8 different types. Then he changed the base of the strops to the magnetic base and I replaced all my strops with mag bottoms! These days he's changed his recommendations, but I've matured into my own sharpening opinions.
I think I may

have over-bought on my first order thinking I'd use the stuff up quickly. My grandchildren will be able to pass this stuff along to their grand children, and I might use some of the unused strops to turn into billfolds...
Stitchawl