what is this rock

[lackaff]

My metal detector found this rock in the creek today
my rock Id app says this is a Tektite but I google Tektite and they are gravel
this rock weighs 45 pounds and is heavy and has a face
how could this be Tektite
what kind of rock is this?
why is my metal detector \going crazY ON IT and pinpointer
please help
the face on it is cool
Thanks

 

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[Relicgrubber]

You need to post more pic's only this time dont wet it down. It helps to see its natural colors imo.

 

[Red-Coat]

Welcome to Tnet

I don’t know where you read that tektites are “gravel” sized, but that source is wrong unless it was specifically referring to the types found in America rather than tektites in general. Normally they’re relatively small and in the region of marble to golf-ball size but Indochinites can be quite large (although the larger ones tend to be elongated or discoid). The largest one I know of was a whopping great 29kg (about 64 pounds), but it was a “Muong Nong” type… an Indochinite, which wouldn’t be found in America.

For tektites found in North America then, yes, those are generally rather small and the size doesn’t typically exceed 200g (around 7 ounces) as a maximum.

Nevertheless, it’s not a tektite. My guess is that it’s a basalt, for which some types have sufficient iron to be magnetic. Is the geology of the area where you found it consistent with volcanic rocks or glacial erratics that have come from such areas (including water-transported by glacial melt)?

 

[lackaff]

I made a video and put it on youtube
please take a look and let me know what u think

 

[Red-Coat]

The video doesn't add much to the story, except to confirm that it's not a tektite. It has a semi-crystalline granular mineralogy in a close-grained matrix, not a fused glassy amorphous one as would be the case for a tektite. I don't see anything unusual about it and the 'face' is of course no more than a coincidental resemblance arising from natural features.

You didn't answer my question about the geographical area where it was found and the geology of that area.

 

[lackaff]

This was in Oregon by The Oregon Trail over Mount Hood on the North Fork of the Salmon River by the PInoer bride womens Grave site
i pulled out my Pinpointer when I was at the creek to see if anyone rocks would go off and this one did out of all them rocks at the creek this was the only one to go off
why is this one going off but not any others?

 

[Red-Coat]

You do know that Mount Hood is a strato-volcano? The watersheds for the surrounding river system have been littered with volcanic rocks from ancient eruptions and there are numerous small, rounded, water-worn boulders which have been alluvially deposited. Mostly andesites, but there are some basalts too. Some of those rocks will be magnetic. Some not.

 

[Carl-NC]

This was in Oregon by The Oregon Trail over Mount Hood on the North Fork of the Salmon River by the PInoer bride womens Grave site
i pulled out my Pinpointer when I was at the creek to see if anyone rocks would go off and this one did out of all them rocks at the creek this was the only one to go off
why is this one going off but not any others?

Look around enough and you will find plenty. Oregon creeks are full of hot rocks, I occasionally detect Quartzville Creek south of Mt Jefferson and they are everywhere. Pinpointers are not as sensitive to them, but a Gold Bug 2 sounds like a machine gun when sweeping over the rocks.

 

[lackaff]

My rock App says now it is ANDESITE
which is what Mount Hood is made of
why is it hot with the pinpointer?

 

[Red-Coat]

The magnetic properties of basalts and andesites generally comes from the presence of small amounts of secondary magnetite. Both rock types also often have high magnetic susceptibility. It's important to recognise that 'basalt' and 'andesite' are not single rocks. They're families of rocks, each with a range of compositions that define the type but nevertheless not having a single composition within the type or even within the same location.

 

[lackaff]

I have found a basalt rock before buried on LoLo pass
and now I found a Andesite Rock on the other side of the mountain
your saying it is not Basalt which is good?

 

[Red-Coat]

I have found a basalt rock before buried on LoLo pass
and now I found a Andesite Rock on the other side of the mountain
your saying it is not Basalt which is good?

Both will be present in the area where you found your specimen.

Andesites are an intermediate family between basalts and rhyolites. The distinctions between basalts and andesites are that (among other things) andesites have a silica content higher than 62% and an alkali metal content lower than 6%.

However these are distinctions imposed by geologists for the simplification of naming. The three families represent a spectrum of volcanic rock types which does not exclude those sitting on or close to the boundaries of compositional norms. Geologists often resort to additional namings such as “basaltic andesites” or “andesitic basalts”.

Andesites are usually light grey to dark grey in colour, arising from the high content of minerals such as pyroxenes, although they can range up to very dark in colour. They’re then difficult to distinguish from basalts, which usually have darker colouration.

 

[galenrog]

The gravel in my driveway, mined at a nearby quarry, is basalt. A qualified geologist would likely call it “andesitic basalt”. Much is attracted to common magnets. Basalts and Andesites are extremely common here in western Oregon.

Time for more coffee.

 

[lackaff]

where is the gold

 

[Red-Coat]

where is the gold

At the end of the rainbow.

 

[galenrog]

where is the gold

I have no idea what you mean.

Time for more coffee.