The rich royal blue in lapis lazuli, caused by sulphur, is sprinkled with glittering flecks of iron pyrite, or fool’s gold. Fine lapis from the Hindu Kush may have a violet cast; paler hues from the Andes are less desirable. White or grayish calcite veining often decreases the value of Andean and Siberian varieties.
One of the most precious commodities of the ancient world, lapis from the mountains of Afghanistan was among the grave treasures found in the tomb of Queen Pu-abi of Sumer and in the pyramid of Pharaoh Tutankhamen of Egypt. As a symbol of power and royalty, lapis was a favorite stone of Cleopatra. Not to be outdone, Catherine the Great of Russia paneled whole rooms in the imperial palace with slabs of lapis. The stone’s intense blue led Roman matrons to use crushed lapis in cosmetics and medieval monks to use it to illuminate their manuscripts.
Still highly prized, efforts never cease to enhance or imitate lapis: White spots may be touched up, pale lapis darkened, and other stones dyed with Prussian blue. Synthetic stones and glass colored with cobalt have even been seeded with gold flakes to simulate pyrite inclusions.
The best deposits are in Afghanistan, where it has been mined for more than 6000 years. Also found in Russia and Chile, with small deposits in the US, Burma, Angola, and Pakistan.
Lapis lazuli brings friendship, love, success, and divine favor. The golden flecks seen in some stones are said to represent wisdom gained in the journey through darkness in search of inner light. In ancient Egypt, lapis was thought to guide the passage of the soul into the afterlife.
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Paints are composed of a pigment, binder, and a solvent; the pigment gives the paint its color, and helps protect the surface it is on from the environment.
Zinc phosphate is often used in dental restoration
3ZnSO4 + 2Na3PO4 --> Zn3(PO4)2 + 3Na2SO4
Zinc sulfate heptahydrate and sodium phosphate
We used potassium ferrocyanide trihydrate (K4Fe(CN)6 3H20) as our salt and iron (III) chloride hexahydrate (FeCl3 6H20) as our iron.
Pigments (Prussian Blue & Chrome Yellow) | Cyanide | Ink
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Synthetic information, spectral reflectance and absorbance of paint layers containing Prussian blue and titanium white, optical photomicrograph of a Prussian blue pigment, iron-57 Mössbauer spectral results on various Prussian blue pigments, thermogravimetric and differential scanning calorimetry of several Prussian blue pigments, experimental information and results of particle induced X-ray emission spectral analysis, background information and application of the Scherrer and Williamson–Hall methods to Prussian blue pigments, extraction and fitting procedure for the pair distribution analysis of the pigment short-range order, and detailed results of the X-ray near-edge absorption spectral analysis. This material is available free of charge via the Internet at .