Thread: Occlusions vs. Inclusions/Naturals/Synthetics

Hi all. Please excuse the sophmoric nature of this question, but reading has piqued my curiosity and something isn't clear to me.

1.) What's the difference between an occlusion vs. and inclusions? (I understand them to be the same thing)

2.) Are occlusions/inclusions relegated only to the world of natural stones or are they seen in the synthetic hone world as well?

Again, sophmoric, but I can think of finer crew and it's bugging me.

Bombs away!

Kind Regards,,,

I never heard of an occlusion in geological terms that sounds more like a medical condition. An inclusion is kind of what the word means. Usually within a rock or mineral are other minerals. A good example is rutilated quartz which is quartz with usually needle xtls of the mineral rutile inside it. With honing stones you could have a particular mineral included into the matrix.

Originally Posted by thebigspendur

I never heard of an occlusion in geological terms that sounds more like a medical condition. An inclusion is kind of what the word means. Usually within a rock or mineral are other minerals. A good example is rutilated quartz which is quartz with usually needle xtls of the mineral rutile inside it. With honing stones you could have a particular mineral included into the matrix.

And that mineral could either be harder than the hone material or softer, the later posing absolutely no thread to the edge, right?

How 'bout taking a stab at number 2.) ?

And, yes, I believe one must be a patient of an opthomologist to properly understand occlusion.

The inclusion can be harder or softer or the same.

As to synthetics, I'm afraid I didn't study that in Geology classes. Having said that synthetics are man made so they should be uniform and consistent.

One of the ways you can tell a synthetic gem from the natural kind is the synthetic is too perfect. The natural will have flaws of some kind as well as some inclusions.

"Occlusion (dentistry), the manner in which the upper and lower teeth come together when the mouth is closed."- Wikipedia

How does that relate to hones? Isn't it obvious?

My understanding from a quick search of my old chemistry texts is that an inclusion is when the impurity is actually part of the crystal structure. An occlusion is when the impurity is trapped within the structure. It reads as though it is a strength of bond thing - occlusions are weakly bound. Maybe someone who actually knows about chemistry can confirm, deny or clarify.

But assuming I understood it correctly, I think from a hone point of view they both basically boil down to one thing - impurity in the hone. I suppose some impurities can be good, some can be bad, some can be benign. If I'm right, an inclusion, if bad, can be hard to get rid of because it is part of the crystalline structure of the rock. An occlusion, being an impurity trapped within the structure, might release into the water after being dislodged? Just guessing.

I cannot see why, even with man made manufacturing processes, you couldn't at least get occlusions. Maybe even inclusions, but they may need to be present already in whatever media is being used to construct the hone. Though if they are, my understanding of the hone making process is that any inclusions in the raw materials would be broken down during that process so you wouldn't get long veins of it or whatever.

Anyway, all this theorising is predicated on the assumption that I've correctly understood inclusions and occlusions in the first place. And that could be a big assumption, since it's still not 7am here...

James.

Never read any old texts using the word 'occlusion' but the stuff I read tends to be hone-specific whereas something more technical may well use terms we are unfamiliar with.

Some inclusions are not that bad. Take the highly figured charnley forest hone, for example. The deep red swirls (not the thin red veins) often have a black or darker spot in the middle where you may find what the old texts called "pinny inclusions".

These hard, pin-like crystalline inclusions are harder than the rest of the hone and can scratch or sometimes chip the bevel. However, they are usually few in number and may be prised out of the softer red material with the tip of a knife.

The resulting small cavity is of no consequence when honing.

Regards,
Neil

The two naturals that I have don't have any obvious inclusions. How can you tell the difference between that pattern that the stone may have vs. an inclusion. Being a crystal, will they reflect light differently than the rest of the stone?

Originally Posted by OCDshaver

The two naturals that I have don't have any obvious inclusions. How can you tell the difference between that pattern that the stone may have vs. an inclusion. Being a crystal, will they reflect light differently than the rest of the stone?

I think, in the majority of cases, it is hard to judge. Some naturals have lots of sparkly bits - quartz, mica, etc, that does no harm at all. The Special Hone for Good Razors is definitely sparkly and I have seen a lot of slates, including thuringians, with sparkly bits.

Even some hones that may look quite homogeneous to the eye when dry reveal banding and speckling when wet - the small Celebrated Water Stones often display this effect and Hatzicho has posted wonderful pics of thuringians like this.

In some respects any patterned, veined or spotted hone contains inclusions, otherwise it would be the same colour all the way through.

One stone that often had inclusions was the old Mueller Water Stone. The old variety could be very good indeed and I used to sell them, but the occurrence of harmful (ie scratchy) inclusions was so common that I had to test nearly every stone I sold towards the end - then they became incredibly variable - quite poor in some respects dropping from a decent finisher to little better than mid range, that I stopped stocking them altogether.

The type of inclusions in those hones was either hard or impossible to see with the naked eye, or looked benign. The only way to tell for sure was testing the hone with a razor - a luxury most of us do not have. Then, the inclusion makes itself felt - you can literally feel it, and you can see its effect by examining the scratch pattern on the bevel, where the inclusion leaves usually widely separated deeper score-marks, being harder than the rest of the matrix.

In short, testing is the only sure way.

Regards,
Neil

Originally Posted by Neil Miller

In some respects any patterned, veined or spotted hone contains inclusions, otherwise it would be the same colour all the way through.

Obviously the patterns, spots, veins are some form of variation in the make up of the stone but does that necessarily mean that its due to inclusions? Or maybe my understanding of inclusions is incorrect? Or is the crystal/harder material the definition of toxic (another term I'm not 100% sure about)?