choochoorocks
starting to spend too much on rocks
Rock hounding
Member since April 2020
Posts: 145
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Post by choochoorocks on May 4, 2020 1:17:59 GMT -5
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Post by pauls on May 4, 2020 16:19:06 GMT -5
Hi welcome from Australia. To me numbers 1 and 4 look like a hard silica, possibly Agate or chert or flint. 3 could be the same but the crusty outside makes it difficult, 2 could be a black version but who knows. Some rocks are just rocks and don't need a name they just look nice.
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fuss
spending too much on rocks
Member since October 2018
Posts: 250
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Post by fuss on May 4, 2020 20:50:09 GMT -5
That is Chert.
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Post by rmf on May 4, 2020 22:20:54 GMT -5
#1 and #4 are agate. #3 looks like some striations maybe coral, #2 looks like #2 to me. Need to have a fresh fracture to see what it is.
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fuss
spending too much on rocks
Member since October 2018
Posts: 250
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Post by fuss on May 6, 2020 6:43:01 GMT -5
#1 and #4 are agate. #3 looks like some striations maybe coral, #2 looks like #2 to me. Need to have a fresh fracture to see what it is. Curious, what makes you suspect #1 and 4 are agates?
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choochoorocks
starting to spend too much on rocks
Rock hounding
Member since April 2020
Posts: 145
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Post by choochoorocks on May 6, 2020 12:34:01 GMT -5
Thanks all for your replies! Re no. 2: there are no fractures on it unfortunately. Re no. 3: I'm including another view of it that hopefully shows its surface features more clearly.
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Post by rmf on May 8, 2020 4:33:40 GMT -5
#1 and #4 are agate. #3 looks like some striations maybe coral, #2 looks like #2 to me. Need to have a fresh fracture to see what it is. Curious, what makes you suspect #1 and 4 are agates? #1 & #4 have a conchoidal fracture plus the translucency. I would also assume a hardness of 7 so that would be an easy way to verify.
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fuss
spending too much on rocks
Member since October 2018
Posts: 250
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Post by fuss on May 8, 2020 20:00:53 GMT -5
Curious, what makes you suspect #1 and 4 are agates? #1 & #4 have a conchoidal fracture plus the translucency. I would also assume a hardness of 7 so that would be an easy way to verify. Your on the right track, but you also described several forms of chalcedony, fracture, opacity hardness etc. but to be classified as an agate you typically need to see banding patterns (usually concentric), there are some exceptions in the lapidary side of things like moss agate, fire agate etc. In this case without the evident banding its safer to say its chert.
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choochoorocks
starting to spend too much on rocks
Rock hounding
Member since April 2020
Posts: 145
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Post by choochoorocks on May 10, 2020 1:01:13 GMT -5
Thanks all! I hope to get a small cutter in the near future look inside some of these rocks.
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brubble
off to a rocking start
Member since April 2020
Posts: 23
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Post by brubble on May 12, 2020 17:22:35 GMT -5
Thanks all! I hope to get a small cutter in the near future look inside some of these rocks. I use an inexpensive tile saw to reveal the innards.
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choochoorocks
starting to spend too much on rocks
Rock hounding
Member since April 2020
Posts: 145
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Post by choochoorocks on May 12, 2020 21:18:10 GMT -5
Do you have recommendations for a saw that will work indoors (garage) without making too much of a mess?
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Post by rmf on May 13, 2020 6:24:18 GMT -5
If you use a typical lapidary saw it runs with oil as a coolant (usually). When cutting the blade sprays off excess oil where the blade hits the stone at about 30 deg to each side. So if you are holding the rock it covers your for arms with spray and can extend out from there. If you have a lapidary slab saw they tend to have lids that keep the spray contained. I am assuming a tile saw will run with water and be open but will still spray water and the associated mud it makes so plan to have a buffer area of about 18" around the saw or setup plastic to direct the spray off of what you do not want sprayed.
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