Chemistry: Calcium aluminum silicate
Crystal system: Monoclinic; prism; deep vertical striations; seldom with distinct terminations.
Color: Transparent to translucent; Epidote: yellow, green, greenish (pistachio) brown; Clinozoisite: (low iron content) light green of greenish brown; red also known; Unakite: type of granite rock, mottled green, pink and gray.
Hardness: 6 - 7
Cleavage: Perfect: basal; Fracture: splintery, conchoidal.
Specific gravity: 3.28
Refractive index: 1.736 – 1770; Biaxial positive; Clinozoisite: 1.724 – 1.7324; Unakite: 1.52 – 1.76; 0.036 (may be lower 0.010)
Luster: Vitreous to metallic.
Dispersion: Medium
Dichroism: Strong: green, brown, yellow; chrome-light green/dark green.
Occurrence: Metamorphic and igneous; Mexico, Mozambique, Norway, USA, Austria; Unakite: South Africa, USA, Zimbabwe.
Notes
Closely related to zoisite; epidote group: zoisite and clinozoisite, epidote, piedmonite, hancockite, thulite (pink zoisite); unakite: ornamental rock containing quartz, pink feldspar and green epidote; intense band at 455nm or none depending on direction; also spectral band at 475nm; difficult to cut, faceted; unakite: beads and carvings.
Tuesday, July 17, 2007
Monday, July 16, 2007
The Wheeler Dealers
Memorable quote (s) from the movie:
Feinberg, Taxi Driver (Robert Strauss): You're just like my wife, mister. You don't understand the economics of the situation.
Henry Tyroon (James Garner): Then teach me. I'm interested in the economics of about every situation.
Feinberg, Taxi Driver (Robert Strauss): Well, there are 11,000 cabs in the city - and no new permits for the next twenty-five years. Now suppose you wanna buy a cab and start hackin'... you gotta get a new permit, too. Now the tab on a new permit is eighteen thousand five hundred on the open market.
Henry Tyroon (James Garner): And how much did your cab cost, Mister, Feinberg?
Feinberg, Taxi Driver (Robert Strauss): Thirty-three hundred... new.
Henry Tyroon (James Garner): Mm-hmm. Then that makes your investment, uh, with the permit, come to about $22,000.
Feinberg, Taxi Driver (Robert Strauss): Yeah. But don't tell my wife... she'll think I'm rich.
Henry Tyroon (James Garner): Mm-hmm. Mr. Feinberg, I'll give you $24,000 for your cab and permit.
Feinberg, Taxi Driver (Robert Strauss): You wanna buy the cab?
Henry Tyroon (James Garner): Right. But you come along with it. I'll need your services for a week, maybe two.
Feinberg, Taxi Driver (Robert Strauss): No, look, mister, I can't sell the cab. I need it.
Henry Tyroon (James Garner): Well, I figured that. So, when I leave I'll sell it back to you for... $22,000.
Feinberg, Taxi Driver (Robert Strauss): You wanna lose two grand just to keep your feet dry when it starts to rain?
Henry Tyroon (James Garner): I don't lose, Mr. Feinberg. See, I borrow the money and then I get a deduction on the loan interest and another on the depreciation and another on the loss when I sell it back to you. And you make a nice profit.
Feinberg, Taxi Driver (Robert Strauss): You win and I win. Uh-uh, there's gotta be a loser somewhere.
Henry Tyroon (Robert Garner): Taxman loses. He usually does on a Henry Tyroon deal.
Feinberg, Taxi Driver (Robert Strauss): Mister, you've just got yourself a taxi.
Feinberg, Taxi Driver (Robert Strauss): You're just like my wife, mister. You don't understand the economics of the situation.
Henry Tyroon (James Garner): Then teach me. I'm interested in the economics of about every situation.
Feinberg, Taxi Driver (Robert Strauss): Well, there are 11,000 cabs in the city - and no new permits for the next twenty-five years. Now suppose you wanna buy a cab and start hackin'... you gotta get a new permit, too. Now the tab on a new permit is eighteen thousand five hundred on the open market.
Henry Tyroon (James Garner): And how much did your cab cost, Mister, Feinberg?
Feinberg, Taxi Driver (Robert Strauss): Thirty-three hundred... new.
Henry Tyroon (James Garner): Mm-hmm. Then that makes your investment, uh, with the permit, come to about $22,000.
Feinberg, Taxi Driver (Robert Strauss): Yeah. But don't tell my wife... she'll think I'm rich.
Henry Tyroon (James Garner): Mm-hmm. Mr. Feinberg, I'll give you $24,000 for your cab and permit.
Feinberg, Taxi Driver (Robert Strauss): You wanna buy the cab?
Henry Tyroon (James Garner): Right. But you come along with it. I'll need your services for a week, maybe two.
Feinberg, Taxi Driver (Robert Strauss): No, look, mister, I can't sell the cab. I need it.
Henry Tyroon (James Garner): Well, I figured that. So, when I leave I'll sell it back to you for... $22,000.
Feinberg, Taxi Driver (Robert Strauss): You wanna lose two grand just to keep your feet dry when it starts to rain?
Henry Tyroon (James Garner): I don't lose, Mr. Feinberg. See, I borrow the money and then I get a deduction on the loan interest and another on the depreciation and another on the loss when I sell it back to you. And you make a nice profit.
Feinberg, Taxi Driver (Robert Strauss): You win and I win. Uh-uh, there's gotta be a loser somewhere.
Henry Tyroon (Robert Garner): Taxman loses. He usually does on a Henry Tyroon deal.
Feinberg, Taxi Driver (Robert Strauss): Mister, you've just got yourself a taxi.
Messaging Is The Medium
Daving Ng writes about The Sims: In The Hands of Artists concept + student art work (s) based on games + the way technology facilitates to create superb imageries + other viewpoints @ http://www.artnewsonline.com/issues/article.asp?art_id=2316
Romance Killer
Victoria Murphy writes about Mark Vadon, the boy from Seattle + his BlueNile.com concept + tips on dealing in diamonds + other viewpoints @ http://www.forbes.com/free_forbes/2004/1129/097.html
Colors Are A Girl's Best Friend
(via Newsweek International) Anna Kuchment writes about the growing interest in colored diamonds + the promotional launch of its first collection of colored stones by the online merchant BlueNile.com + other viewpoints @ http://www.msnbc.msn.com/id/19650872/site/newsweek
Jewelry Top Investment Of Passion
According to World Wealth Report (Merrill Lynch + Capgemini), for high net worth individuals, jewelry falls into the third category for investments of passion.
More info @ http://www.us.capgemini.com/worldwealthreport07/wwr_pressrelease.asp?ID=629
More info @ http://www.us.capgemini.com/worldwealthreport07/wwr_pressrelease.asp?ID=629
The Pleasures Of Discovery
(via The Journal of Gemmology, Vol.XIV, No.3, July 1974) B W Anderson writes:
(being the substance of a talk given to the Gemmological Association of Great Britain at Goldsmith’s Hall on 29th October, 1973)
Sinhalite
Less than a year after the paper on taaffeite was read before the Mineralogical Society, Dr Claringbull was able to announce the establishment of yet another new gem mineral, which he named sinhalite from its origin in Ceylon. But on this occasion we were spectators rather than protagonists, though we were able to provide many specimens to aid the work, as sinhalite had been knocking around for sometime under the disguise of brown peridot. Robert Webster indeed nobly sacrificed part of his only specimen for Dr Hey to analyze. Whereas, when the taaffeite paper was read, all we had to show was two small cut specimens, Claringbull had a score of sinhalites to show (one giant of 75 carats) which had crept from their wrongly labeled packets for the occasion. There was even a small pebble of sinhalite which had been picked from a sample of illam by Dr E H Rutland.
Credit for the sinhalite discovery belongs properly to Dr George Switzer of the Smithsonian Institution, who took an X-ray powder photograph of scrapings from the girdle of a ‘brown peridot’ in the U.S Museum collection and found spacings which clearly differed from those of olivine. Knowing this, Dr W F Foshag (Switzer’s chief in the Institution) cast doubts on a specimen of ‘brown peridot’ in the Natural History Museum when Dr Claringbull was showing him round the mineral gallery, which gave rise to an energetic attack on the problem.
Sinhalite contains no silica, being a magnesium alumunium borate, MgAlBO4. Like peridot, it is orthorhombic, and its refractive indices, birefringence and density are very close to those of brown iron-rich peridots or olivines which are occasionally met with in Arizona and elsewhere; the chief difference being in the b index, which in peridot is nearly mid-way between the greatest and least indices, while sinhalite is clearly negative in sign. The absorption spectra are also very similar in the two minerals, but sinhalite shows an extra band at 4630 Angstrom. Sinhalites have been found in packets of golden zircons and of yellow chrysoberyls—they vary in color from pale straw yellow, but at their best are very attractive, being clean, transparent, and obtainable in important sizes. In fact, of all the newly discovered stones that I am talking about this evening sinhalite is the only one that has the slightest commercial importance. On the ‘anything you can do’ principle which I mentioned earlier, it was Burma which provided the first well-shaped sinhalite crystal, which C J Payne had the privilege of measuring.
Painite
In painite we have the rarest mineral of them all: in fact I find it rather amusing, considering that no cut stone exists (2007: today there are cut specimens available at affordable prices ), that a description of the stone occurs in at least five books on gemstones. The original dark red crystal, well-formed though rather waterworn, was found in one of the small ruby mines near Ohngaing village in the Mogok district of Burma. Mr A C D Pain, who suspected it might be something new, sent it to the laboratory for testing. The crystal at first sight looked as though it were tetragonal, but C J Payne, finding the prism angles to be exactly 60º realized that in fact it was hexagonal. It weighed 8.5 carats. The density was found to be 4.01 and the refractive indices 1.8159 for the ordinary and 1.7875 for the extraordinary ray, giving a birefringence of 0.0284. The hardness was measured as 8 on Moh’s scale by an indentation method. The dichroism showed a brownish red for the ordinary ray and deep ruby red for the extraordinary.
Permission was given for a thin slice to be removed from the base of the crystal for Claringbull and Hey to carry out the necessary X-ray and chemical work. Analysis showed the mineral to be borosilicate of calcium and aluminium, but it proved difficult to ascribe to it a definite formula. The specimen was justly named after its discoverer, and presented by him to the Museum where most of the work on it was done.
Chromium lines were visible in the red end of the spectrum, and the color was probably due to this, at least in part. In confirmation of this, the stone showed a red glow under crossed filters. It is difficult to judge how attractive a cut painite might be. In bulk, the color was too deep to be effective, but one might guess that small stones might look very much like Siam rubies.
The Pleasure Of Discovery (continued)
(being the substance of a talk given to the Gemmological Association of Great Britain at Goldsmith’s Hall on 29th October, 1973)
Sinhalite
Less than a year after the paper on taaffeite was read before the Mineralogical Society, Dr Claringbull was able to announce the establishment of yet another new gem mineral, which he named sinhalite from its origin in Ceylon. But on this occasion we were spectators rather than protagonists, though we were able to provide many specimens to aid the work, as sinhalite had been knocking around for sometime under the disguise of brown peridot. Robert Webster indeed nobly sacrificed part of his only specimen for Dr Hey to analyze. Whereas, when the taaffeite paper was read, all we had to show was two small cut specimens, Claringbull had a score of sinhalites to show (one giant of 75 carats) which had crept from their wrongly labeled packets for the occasion. There was even a small pebble of sinhalite which had been picked from a sample of illam by Dr E H Rutland.
Credit for the sinhalite discovery belongs properly to Dr George Switzer of the Smithsonian Institution, who took an X-ray powder photograph of scrapings from the girdle of a ‘brown peridot’ in the U.S Museum collection and found spacings which clearly differed from those of olivine. Knowing this, Dr W F Foshag (Switzer’s chief in the Institution) cast doubts on a specimen of ‘brown peridot’ in the Natural History Museum when Dr Claringbull was showing him round the mineral gallery, which gave rise to an energetic attack on the problem.
Sinhalite contains no silica, being a magnesium alumunium borate, MgAlBO4. Like peridot, it is orthorhombic, and its refractive indices, birefringence and density are very close to those of brown iron-rich peridots or olivines which are occasionally met with in Arizona and elsewhere; the chief difference being in the b index, which in peridot is nearly mid-way between the greatest and least indices, while sinhalite is clearly negative in sign. The absorption spectra are also very similar in the two minerals, but sinhalite shows an extra band at 4630 Angstrom. Sinhalites have been found in packets of golden zircons and of yellow chrysoberyls—they vary in color from pale straw yellow, but at their best are very attractive, being clean, transparent, and obtainable in important sizes. In fact, of all the newly discovered stones that I am talking about this evening sinhalite is the only one that has the slightest commercial importance. On the ‘anything you can do’ principle which I mentioned earlier, it was Burma which provided the first well-shaped sinhalite crystal, which C J Payne had the privilege of measuring.
Painite
In painite we have the rarest mineral of them all: in fact I find it rather amusing, considering that no cut stone exists (2007: today there are cut specimens available at affordable prices ), that a description of the stone occurs in at least five books on gemstones. The original dark red crystal, well-formed though rather waterworn, was found in one of the small ruby mines near Ohngaing village in the Mogok district of Burma. Mr A C D Pain, who suspected it might be something new, sent it to the laboratory for testing. The crystal at first sight looked as though it were tetragonal, but C J Payne, finding the prism angles to be exactly 60º realized that in fact it was hexagonal. It weighed 8.5 carats. The density was found to be 4.01 and the refractive indices 1.8159 for the ordinary and 1.7875 for the extraordinary ray, giving a birefringence of 0.0284. The hardness was measured as 8 on Moh’s scale by an indentation method. The dichroism showed a brownish red for the ordinary ray and deep ruby red for the extraordinary.
Permission was given for a thin slice to be removed from the base of the crystal for Claringbull and Hey to carry out the necessary X-ray and chemical work. Analysis showed the mineral to be borosilicate of calcium and aluminium, but it proved difficult to ascribe to it a definite formula. The specimen was justly named after its discoverer, and presented by him to the Museum where most of the work on it was done.
Chromium lines were visible in the red end of the spectrum, and the color was probably due to this, at least in part. In confirmation of this, the stone showed a red glow under crossed filters. It is difficult to judge how attractive a cut painite might be. In bulk, the color was too deep to be effective, but one might guess that small stones might look very much like Siam rubies.
The Pleasure Of Discovery (continued)
Ekanite
Chemistry: Metamict-Calcium thorium silicate
Crystal system: Amorphous from Tetragonal; usually micro crystals; rarely large.
Color: Transparent to translucent; metamict: green, yellow, light brown; crystalline: yellow-red; phenomena: may show 4-rayed star.
Hardness: 6.0 – 6.5
Cleavage: -
Specific gravity: 3.28
Refractive index: 1.597 metamict; SR.
Luster: Vitreous.
Dispersion: -
Dichroism: -
Occurrence: Gem gravels of Sri Lanka; some crystalline material found in Canada.
Notes
Found in 1953; mildly radioactive; may be cut as collector’s stone.
Crystal system: Amorphous from Tetragonal; usually micro crystals; rarely large.
Color: Transparent to translucent; metamict: green, yellow, light brown; crystalline: yellow-red; phenomena: may show 4-rayed star.
Hardness: 6.0 – 6.5
Cleavage: -
Specific gravity: 3.28
Refractive index: 1.597 metamict; SR.
Luster: Vitreous.
Dispersion: -
Dichroism: -
Occurrence: Gem gravels of Sri Lanka; some crystalline material found in Canada.
Notes
Found in 1953; mildly radioactive; may be cut as collector’s stone.
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