[MarkMardon754]

As you may know, I recently got a sample of this metal for a collection...
I like playing with it because if of its incredible density and hardness, it's very cool.

- A few days ago I was cleaning the sample and accidentally dropped it, as soon as it hit the ground there was this "Thunk!" sound, as if something very heavy had hit;
The impact just made a teeny-tiny dent on it, almost imperceptible.

- When it's washed, the metal becomes shiny white, and then after a few minutes, it oxidizes and becomes darker in color (not much, but it's noticeable).

- I've read that all natural isotopes of Tungsten -- 180W, 182W, 183W, 184W and 186W are predicted to be radioactive with extremely long half-lifes, and decay by alpha emission, although as you can see in this page http://www.periodictable.com/Isotopes/074.186/index.html, these isotopes can also emit some beta particles, becoming Hafnium.

[Enthalpy]

Among natural tungsten isotopes, only ¹⁸⁰W as been observed to decay, with a half-life of 2×10¹⁸ years. So if you observe radioactivity from your sample, it doesn't results from natural tungsten.

A tiny dent is normal for any metal except the ultra-soft ones. Once I accidentally impacted steel against steel at 800km/h, and the dent was some 2mm deep.

Decade-old unused tungsten electrodes for arc welding are shiny, but I can't tell if they shine more after cleaning.

[MarkMardon754]

When I wash it with soapy water, the W develops a white shine, akin to that of tin (which i read is an indicator of its purity).
Then quickly darkens to a steel gray color, the oxide layer formed prevents any more darkening from occuring.

Anyway, thanks for your reply. And if anyone else is interested in collecting chemical elements,
I strongly suggest Tungsten as your first sample. It's a fascinating material.

[Enthalpy]

Documentation by a manufacturer, Plansee:
https://agenda.infn.it/getFile.py/access?resId=2&materialId=paper&confId=1862