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Elements Collection

You see, the chemists have a complicated way of counting: instead of saying "1, 2, 3, 4, 5 protons", they say "H, He, Li, Be, B."
H He
Li Be B C N O F Ne
Na Mg Al Si P S Cl Ar
K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr
Rb Sr Y Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te I Xe
Cs Ba Lu Hf Ta W Re Os Ir Pt Au Hg Ti Pb Bi Po At Rn
Fr Ra Lr Rf Db Sg Bh Hs Mt Ds Rg Cn Nh Fl Mc Lv Ts Og
La Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb
Ac Th Pa U Np Pu Am Cm Bk Cf Es Fm Md No

Z=12 ~ Carbon

SC290 - Yellow fluorescent diamond from South Africa

Locality: South Africa (MINDAT)
Size: 5 x 5 x 3 mm
Weight: 1.2 ct
minID: 4E0-3U6

Little rough diamond. Nice yellow/green fluorescence under longwave UV light, much much weaker under shortwave.

Visible light
Longwave UV

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Z=29 ~ Copper

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Z=82 ~ Lead

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Z=90 ~ Thorium

Thorium metal

Thorium in metallic form has a nice silver color, which blackens when exposed to air due to the formation of a superficial layer of thorium oxide (ThO2). In the figure, a small sample in a glass vial. It is a strip 6 mm long, 3 mm wide, but I have no idea of its thickness. Assuming a thickness of 0.1 mm, the sample would weight about 20 mg. It should be at least 98.5-99% pure. Due to the very small mass, its activity is very low. As of May 2018, the SGS-5 geiger counter measures 7 CPM (background already subtracted), or 0.04 μSv/h.

Welding electrodes

Gas Tungsten Arc Welding (GTAW), also known as Tungsten Inert Gas (TIG) welding, is an arc welding process. The electrodes used for this are, as the name suggests, made of tungsten, both pure or as an alloy with other metals. Same of these contain thorium in the form thorium oxide (thoria, ThO2). Three thoriated alloys have been standardized: WT20 (red tip) contains about 2% of thoria, WT30 (violet tip) contains 3%, and WT40 (orange tip) contains 4%.

In the figure, 10 red tip (2% thoria) electrodes with a diameter of 1.6 mm and a length of 15 cm. Assuming a density for this alloy of about 19 g/cm3, each electrode weights about 5.75 g, of which 0.11 g are of thoria. Thoria contains about 88% or thorium, so each electrode contains about 0.1 g of thorium. Summing the content of the 10 electrodes, they should contain a total of about 1 g of thorium. This makes calculations for the theoretical activity easy, as the specific activity of Th-232 is 5 kBq/g. This is valid only if the thorium is “new”; a 10-fold increase in activity in expected during the first 50 years of aging. As of May 2018, the SGS-5 geiger counter measures 118 CPM (background already subtracted), or 0.69 μSv/h.

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Z=92 ~ Uranium

SC111 - Uraninite with Schröckingerite from Utah, USA

Locality: Mi Vida Mine, Big Indian Mining District, San Juan Co., Utah, USA (MINDAT)
Size: 4 x 3 x 2 cm

Small Schröckingerite crystal on Uraninite. The uraninite is not fluorescent, but the Schröckingerite has very nice deep green fluorescence.

Very radioactive: 19.3 uS/h (beta+gamma), 145 times the natural background.

Visible light
Shortwave UV

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Last update: 15 June 2020