[Scriptoris] Round Table meeting (LAPIS discussion)

[Donald Whitney]

Pyro,
 
http://www.firemountaingems.com/details.asp?pn=H206042NB

 The link you sent is C grade lapis lazuli, and has too much white to give you the pretty "lapis" blue if your thinking of using this for pigment unless your willing to grind/file out the white and black first before powdering; otherwise you just get an odd blue if you powder the inclusions with it.  Most lapis has some pyrite inclusions as well, although this doesn't seem to detract much from the overall result (but the grey matrix inclusions would darken it).
 
Good grade lapis is sold by the carat or gram (5 carats), and can often run more than $1/gram.
http://reviews.ebay.com.au/Lapis-Lazuli-Grading-Guide-AAA-AA-A-B-C?ugid=10000000014377472
 
Please look at the AAA and AA grades.  Note the color difference between the A grades and the B/C grade lapis.  C grade seems to contain a lot of calcite, and the Fire mountain material looks like it contains some grey matrix material that would need to be removed before powdering.
 
I have some powdered lapis that I got when Francis, a 90+ year old lifetime gem club member, was cutting a 30x40mm AA lapis cabachon thank-you for one of her doctors who cured her neuropathy; I was fortunate enough to be running the lab that night.  I collected the water off the 80 grit diamond lapidary grinding wheel when she was done, and she was the only one who had used it, and then dehydrated the water in a plastic painter's tray insert, and collected the resulting powder.    The tube of lapis powder (the particles were suspended in about 1/2 gallon of water) gave me a few grams of powdered lapis, and took 10 days to dehydrate in Texas in full sun.  I put a grate over the top to keep things from blowing into it while the water evaporated.  I still need to write up the documentation for this for A&S (look for a small glass vial with 1.5 cm of blue powder in it, with wax paper between the stopper and the vial in my A&S display sometime).  
 
 DO NOT BREATH ROCK DUST! SILICOSIS is very bad for you.  Please wear a face mask when working with powdered minerals to prevent silicosis. Eye protection is also recommended.  Dying of potter's lung is period, but a game is no longer fun when people die for it.
 
  We have a guy  who lives part of the year in Afghanistan and swings by the Arlington gem club, on very short notice, on his way to the annual gem show in Tucson, AZ ;  he sells A grade and above lapis rough to professional and hobbyist lapidaries (people who cut rocks) at very good prices, but it will still cost several hundred dollars for something the size of a golf ball.
 
If there were powdered gem merchants in the middle ages, I wouldn't be surprised if a 13th century lapidary wouldn't sell the water left over from cutting high grade lapis (which is much softer than the cutting wheel) to someone who would then evaporate it for other uses. From a lapidary's perspective, the water is just waste to be thrown out (or in a desert, recycled once the particulates fall out in 2 or 3 days).  You might check with your local gem clubs to see if anyone is cutting lapis and would let you collect the water, but you'd kind of have to catch them doing it, and be a club member to get in the door(so if your not a rockhound, this avenue may not be open to you).  If a lapidary thinks about it, they may make some of this lapis powder to color the epoxy when doing lapis inlay (it will color the epoxy lapis blue).  The same can be done with malachite or other strongly colored mineral that is chemically inert in water.  You only need the water from the 80-100 grit "preforming" wheel, as this is where most of the material is removed.
 
You can buy prepowdered lapis lazuli http://www.artistsupplysource.com/product.php?productid=56680 , but 100g will set you back $174.
 
I taught a class at KC on gem cutting in the middle ages. One or two people (of the 16 in class) seemed interested enough that they might look up their local gem club, so if you can find them, they might be able to get the powdered lapis water for you.  I'm sorry I don't have their names for you.
 
Silvius Foppa, rockhound
 
 
 
 

> From: betsy at softwareinnovation.com
> To: scriptoris at lists.ansteorra.org
> Date: Sat, 21 Jul 2012 18:04:44 -0500
> Subject: [Scriptoris] Round Table meeting
> 
> Here is the link to the lapis I mentioned in the meeting this morning..
> 
> http://www.firemountaingems.com/details.asp?pn=H206042NB
> 
> enjoy!
> 
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