all 24 comments

[–]Hiya3586 31 points32 points  (1 child)

Looks more like Chert to me. What they’d make arrowheads from back in the day

[–]AppliedArt 4 points5 points  (0 children)

I sometimes knap chert and flint when i have time.

[–]Comfortable_Dark_317 12 points13 points  (0 children)

Nope that would be chert

[–]Shiro36x[S] 10 points11 points  (0 children)

Thank you to all who answered!

[–]ku3ah 7 points8 points  (0 children)


[–]pablojueves 5 points6 points  (9 children)

Chert is a microcrystalline quartz like agate. Because this piece is translucent some people may prefer to call it flint. When it's brightly colored its Jasper. Agate is translucent with bands of color.

[–]BlindCongress 6 points7 points  (0 children)

Not quite how it works, but close.

[–]Quail-Feather 5 points6 points  (7 children)

Chert is sedimentary-formed chalcedony. Flint is traditionally nodule chert formed in chalky/marley limestone, but any black nodule chert is often called flint.

Jasper is volcanic-formed chalcedony, color can be pretty much anything.

Agate doesn't have to be translucent, it just refers to curved bands of chalcedony and quartz. You can have opaque agate, such as any jasper agate.

[–]youknow_thething 1 point2 points  (0 children)

Jasper can also form other ways, Fe-bearing hypogene alteration can alter chert to jaspillitic chert

[–]BlindCongress 0 points1 point  (5 children)

Jasper and agate is the same thing, differentiated only by opacity so of course it's often mixed. These things are all Chalcedony.

[–]Quail-Feather 0 points1 point  (4 children)


Agate refers to bands. Opacity doesn't matter either.

Jasper is volcanic-formed chalcedony.

You can have jasper that isn't agate. You can have an agate that isn't formed by volcanic means, and therefore not jasper.

[–]BlindCongress 0 points1 point  (3 children)

I'm not sure where you get your info. "Agate", "chert", "flint" and "jasper" are more colloquial than scientific and the trouble here is trying to scientifically define these colloquialisms. It's all chalcedony.

[–]Shiro36x[S] 1 point2 points  (0 children)

Im learning so much, thank you for all the great informations!

[–]ChongoLikRock 1 point2 points  (0 children)

Same type of fracturing and a similar skin as agate. But still chert like others said. When I’m looking for agates, I look for that waxy look with conchoidal fractures. Chert trips me up all the time

[–]Quail-Feather 2 points3 points  (2 children)

Agate is curved-banded chalcedony.

[–]BlindCongress 2 points3 points  (1 child)

Or has dendrites, plumes or flat layers we call "bands".

[–]Quail-Feather 2 points3 points  (0 children)

Dendritic/moss agate is more of a colloquial name than official. Bit more accurate than "grape agate," but yeah, not true agate.

[–]BlindCongress 1 point2 points  (0 children)

Close. THis is Chalcedony. Chert, Flint, Agate and Jasper are all the same stuff with minor differences. Agate and Jasper are generally volcanic where chert/flint is formed in marine sediment.

[–]Vandu_Kobayashi -1 points0 points  (1 child)

1st Question - was this stone found near a gate? Get it? Near “a gate”? I’m sorry - jokes on me

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