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Re: [Orchid] Orienting Labradorite
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Debra K Hoffmaster Friday, January 18, 2008
   
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    Fortunate timing. I just put this in our club newsletter - Debby 

    ORIENTING OBSIDIAN, LABRADORITE AND SPECTROLITE 
    Jim Small. Small Wonders Lapidary 

    Obsidian: 

    Orienting Obsidian depends on what type of obsidian and what you are
    doing with it. If you are polishing flats. the best way to orient
    rainbow sheen obsidian is 10-15 degrees off the plane of the parallel
    bands. If you are cabbing it, cut exactly parallel to the bands. Sold
    sheen is always cut parallel to the bands or the effect is lost or
    diminished. Fire obsidian sometimes loses its fire sheen when cut
    parallel and should be cut after careful examination of the best
    angles for viewing the fire which is actually in between bands. Other
    types of obsidian look different when cut at different angles to the
    bands; midnite lace is one such example, where you should experiment
    until you find the "look" that pleases you. 

    Labradorite/'spectrolite': 

    Here is a procedure for orienting labradorite/spectrolite. It will
    also do a credible job with moonstone. With most sunstone (India and
    upstate NY) orientation is simpler because you will just orient for
    the schiller (metallic flecks). 

    1) Set a student desk lamp; what we used to call a high-intensity
    lamp. They usually have a switch for two brightnesses. and they
    always have clear glass bulbs (this is important). 

    2) Fix a high shelf where you can put your lamp. so that you can
    adjust the arm to have the beam of light shine straight down onto a
    flat surface which needs to be no higher than thigh-high. A stool or
    flat-top crate will work fine. 

    3) Set a tin, like one of the tins which Danish butter cookies come
    in; it should be anywhere from 8" or ">" in diameter up to 12" in
    diameter. and between 2" and 3" deep. Fill this tin about 3/4 full
    with sand or fresh kitty-litter or any other finely granular
    material. 

    4) Set a really good quality water-proof marker. It should be at
    least 6" long. and ought to have a relatively fine (no more than
    1/8") point. Round-nose markers work fine as long as they haven't
    been squished by pressing too hard. 

    5) Stand on the opposite side of the stool/crate from the shelf with
    the lamp. /Adjust your stance and the lamp so that you can look
    straight down on the middle of the tin while the lamp shines its beam
    straight down above the top of your head. without your head occluding
    the beam. 

    6) Place a piece of mono-crystalline labradorite in-the granular
    material-in the tin. so that at least 2/3 of it is above the
    supporting grains. If you have polycrystalline pieces of labradorite
    you either have to cut them apart along the crystal boundaries. or go
    for the largest or showiest crystal, and trash the others. 

    7) Slowly rotate the labradorite until you see a flash of color;
    once you locate a flash slowly spin the piece until you have the very
    brightest flash showing right on top. After you have the brightest
    surface centered rest your permanent marker on the top edge of the
    tin. and drag it slowly around the piece. leaving a mark all of the
    way around. This mark should be parallel to the top flash. 

    8) Slice your crystal parallel to the mark to cut slabs which will
    produce finished cabs with a broad color flash over their top
    surface. 

    Some labradorite will behave like moonstone. and have the capability
    of producing a floating eye in a cut cab. To test whether your stone
    has this capability take the following additional steps. 

    9) Place the stone on its side. so that the marker line is straight
    up toward your eye. Slowly rotate the stone. keeping the line in
    vertical orientation. When you see "another flash (it will be
    distinctly weaker than the broad flash which you already marked),
    test its location by slowly revolving the stone from left to right or
    vice versa until you have the best flash firmly centered on the top
    of the stone. It should be somewhere on the first line; if it isn't,
    start over from the beginning. 

    10) After the second flash is firmly centered. draw another line in
    the same fashion as the first one. The two lines will not meet at a
    90 degree angle. but nearly so. 

    11) Slice the crystal parallel to the second line to produce a
    floating eye in your finished stone. 

    Now. to make things really interesting. there is some labradorite
    from Labrador that not only has labradorescence. but it also has
    schiller. In effect, it is labradorite/ sunstone. If you have any of
    this material you will see the small metallic flecks show up when you
    do the first orientation. If you have this material. don't bother to
    look for the floating eye because the schiller is much rarer as an
    optical phenomenon. 

    You can get into really fancy tricks with the orientation if you
    want to. like having pendant stones that flash only when they are
    hanging on someone. Labradorite is not recommended as a ring stone,
    nor a bracelet stone: it is much too soft and tender for anything
    that rugged. Also, since it is a feldspar it has perfect cleavage in
    two directions; a sharp rap will cleave it! 

    From The Glacial Drifter: 50(8):5 November 2007 via GEM CUTTERS NEWS
    11-06

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