Test Readings From An Iron Rock

[RSB]

The rock in the attached picture is a combination of magnetite and hematite with a small magnet adhering to its front. Magnetite is strongly attracted by a magnet but hematite is not. Hematite is red and you should be able to see the reddish splotches on the face of the rock. Magnetite is black. Both of these minerals are iron oxides. There is not a consistent attraction of the magnet around the rock, which indicates that the minerals are not evenly distributed throughout. Why talk about this rock at all? I was interested in learning how the 2500 would react when passing over the rock. First, in the Coin Discrimination mode there was no reaction if the rock were more than an inch away. Closer than an inch the conductivity was that of a dollar and image was a

 

[NM5K]

Almost looks like a meteorite. :/ Note the glazed look to it, kind of like it survived a re-entry..

 

[bigealive]

exploded upon entry of atomsphere? That there looks to be a mete. frag., but what do I know???????

 

[Joel-Winnipeg]

Meteorite by the looks of that rock ,
strong magnetic attraction and fused look.
Is it heavy ?

 

[RSB]

Unfortunately, this is a very earthbound rock. The visual clue for ruling out this rock as a meteorite is the porosity. Meteorites are very dense and have no bubble holes. In the picture, the area around the magnet and to the left of the magnet looks something like a meteorite fusion crust but even that area shows porosity. One simple test that can be made to keep the specimen on track to a positive meteorite ID is to make a streak test. Use a piece of unglazed ceramic tile and scratch the specimen across the tile and check the color that is produced. A meteorite will have no streak or a one of gray color. The rock in the picture produced a big reddish-brown streak that disqualified it for meteorite status. Also, I polished a small area on the top of the rock and the polished area was porous as well. The grinding wheel was red from the polishing action. If your sample passes your visual inspection and the streak test, take it to your local University for analysis. Meteorites should have at least 5% nickel. I thought there might be some interest in how the metal detector reacted to the iron rock. Anyway, thanks for the comments and for looking.

 

[fongu]

I may have this backwards, but if you are trying to rule out a hot rock with the 2500, can't you scan it in zero mode and if there is no signal it's a hot rock?

 

[RSB]

Using the 2500 in the Zero Discrimination and Coin Discrimination modes the detector will sound a bell tone and indicate a conductivity of one dollar if the coil is practically touching the rock. Any distance greater than an inch, there is no sound or any other indication of the presence of the rock. In the All Metal mode as the coil approaches the rock, the threshold sound goes to zero and continues at zero until the trailing edge of the coil has just passed the rock and then the sound peaks and diminishes as the coil is moved away. This happens in either direction of the swing. Other detector models may not work the same way in the All Metal mode.