FMF - Friends of Minerals Forum, discussion and message board

[momurda]

I found this while i was on a fishing trip in maine. The geologist said it was a volcanic rock but couldnt tell me anymore. I am going to take it to a university and have it chemically tested. This weighs almost 12 pounds I origionally thought it was a meteor. Has anyone ever seen a rock like this before? Thanks in advance for the replys.

[Peter Megaw]

It looks like a piece of stream-rolled vesicular basalt. The "closed" shape/nature of the vesicles/holes eliminaties the possibility that these are ablation features on a meteorite.

Call it a "meteorwrong" for maximum impact

[momurda]

So is it a worthless rock?

[nurbo]

Is there such a thing as a "Worthless rock"? it looks pretty interesting to me.

[Les Presmyk]

It is hardly worthless. If you find it interesting and it reminds you of a pleasant vacation then the memory is definitely worthwhile. From a mineral specimen standpoint, it is just a rock. And, when you take it to the university, they will tell you the same thing as Peter Megaw did, probably even a bit less eloquently, and most certainly without the marginal joke.

[Vinoterapia]

I do agree with what already have been said, it does look like a basalt. However, your indication that it weights almost 12 pounds puzzle me, that is too much for a piece of basalt of that size, specially if internally have as many vugs as shown on the surface. If you take it to the university have it sliced to see its internal structure and let us know.

[Pete Modreski]

Ah, this last comment, a challenge I couldn't resist, how much would a rock (of basalt) this size weigh?

I just measured, a U.S. dollar bill is a little over 15 cm long. Allowing for the perspective distortion in viewing as in the photo--the rock looks somewhat smaller than the bill, but it is also a bit further from the camera--let's estimate the diameter of the rock as 15 cm, so radius = 7.5 cm.

Volume = 4/3 x pi x r(cubed) = 1767 cc

assuming density of basalt = 3 grams/cc, mass of rock = 5300 grams = 5.3 kg

5.3 kg = 11.7 pounds. I was going to allow a factor to reduce that for the porosity of the rock, but since it comes out exactly to what we were looking for (12 lbs), I will just quit while I am ahead!

It definitely just looks like a piece of vesicular basalt. An interesting rock, but of no particular value, other than as a curiosity to the finder.

cheers, Pete

[Pete Richards]

You're certainly right, Pete! Part of the art of doing science is knowing when to stop refining your estimates!

[momurda]

wow all this math lol im just a humble computer geek with a wierd rock. I googled what the first guy said and i believe he hit the nail on the head. I had been googling all sorts of rocks but couldnt find anything close to mine, after he said the basalt i googled that and yup it looked just like one of them and it was out of a stream so i was like yup he has to be right. Thank you all for taking the time to look at my rock i was hoping to sell it but i guess its just now going to be a mantle piece =)