# Is this a Pyrite crystal cube? [closed]

There is a metallic shine on it that does not clearly show in the photo

This cube weighs 458g

Dimensions: 55mm H x 45mm W x 39mm D

Is this a Pyrite cube?

Thank you

• It could be block of pure iron. How can we confirm if this is pyrite just from the photo? Have you conducted any physical/chemical test? Commented Apr 13, 2023 at 7:47
• Working out the density would probably be simplest. Commented Apr 13, 2023 at 8:19
• It isn't even clear in the photo what colour it is. Pyrite is brassy/golden in colour. Is this cube that colour? Commented Apr 13, 2023 at 8:48
• @NilayGhosh the density is too low for iron and galena, which I also checked, but comes close for pyrite. See below for suggested additional tests. Commented Apr 13, 2023 at 12:12
• Iron is out if it does not pass the magnet test, i.e., if a magnet is not attracted to the specimen.
– Ed V
Commented Apr 13, 2023 at 14:50

Pyrite is a reasonably good guess. Calculating the density of the cube from the reported measurements gives 4.7 g/cm³, using the same number of significant digits as those reported in the length measurements (and assuming a geometrically perfect block). Assuming the length measurements are correct to within $$\pm0.5$$ mm the possible range of densities is 4.6-4.9 g/cm³. This overlaps he reported density of pyrite 4.8-5.0 g/cm³. You may also check the hardness (pyrite = 6-6.5 Mohs, from the source cited above) and streak (greenish-black, Ibid.); the latter is often a better color measure than the apparent surface color because it is less subjected to surface impurities. If you have access to a lab that does X-ray diffraction, then pyrite has a distinctive and well-recognized pattern and the test, unlike the others I mention, is completely nondestructive.