Thursday, June 13, 2013

Luminol and Iron Minerals

Luminol is a chemical with the formula C8H7N3O2 and the official name 5-Amino-2,3-dihydro-1,4-phthalazinedione. It is used in forensic analyses to find blood traces on crime scenes and in biology to find iron, copper or cyanide in cells. Luminol is reacting with oxidizing chemicals like hydrogen peroxide (H2O2) and produces a blue glowing chemoluminescence. Under normal conditions this luminescence in invisible but the use of catalyst chemicals like iron or copper cause an intensive cold blue light. 

The catalytic effect could also be used to display iron minerals and their distribution. In the photos below show an ammonite from the Lower Jurassic of Southern Germany. The fossil is made of pyrite (FeS2) with low contents of marcasite (also FeS2, but with another crystal class). On the surface the minerals are partly transformed to iron oxide. With luminol the minerals show a clear blue chemoluminescens that is most intensive on the parts that are oxidized.

Ammonite (photo size 3 cm)
Ammonite with luminol.

Another iron containing mineral is glauconite an iron rich clay mineral. It seems also to react in the presence of luminol. The photos below show an ammonite from the Upper Jurassic that is covered by a thin film of glauconite minerals. The more intensive luminescence is on areas where remains of sediment cover the fossil. This sediment can contain pyrite or iron oxides that are reacting.

Ammonite covered by glauconite (photo size 6 cm).

The ammonite with luminol.

Further experiments with lumino: luminol and the cauliflower structure and luminol experiments.

1 comment:

  1. Not only great photos but I learned something very interesting today, thank you so much great post!
    Thank you also for stopping by my blog and wishing you a great weekend.
    An English Girl Rambles


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