Any idea what kind it is?

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[–] 2 points 8 months ago (1 child)

I asked chat gpt because I was curious...


The rock appears to be iron-stained sedimentary rock, most likely:

Sandstone or siltstone

Reasons:

Brown/yellow coloration typical of iron oxide (limonite/goethite) staining

Visible layering and flaking, suggesting sedimentary bedding

Fine-grained surface (no large visible crystals)

Breaks along planes rather than showing crystalline fracture

The reddish area

The darker red patch may be:

A small iron-rich concretion

Or possibly a fragment of jasper (iron-rich microcrystalline quartz) embedded in the host rock

Less likely options

Not granite (no visible interlocking crystals)

Not basalt (wrong color and texture)

Not metamorphic schist (no clear foliation or mica sheen)

If found in Scandinavia, this type of iron-stained sandstone/siltstone is common in sedimentary formations and glacial transport deposits.

For more certainty:

Check if it scratches glass (quartz-rich sandstone will)

Drop vinegar on it (if it fizzes, it contains calcite → limestone component)

Note where it was found (coastal, inland, quarry, etc.)

Most probable identification: Iron-rich sandstone or siltstone.

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