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GeneralWhat is term for this type of crystal growth? Interlocking Quartz Points
16th Jun 2013 18:06 UTCDavid Dillman OP
My daughter found these two hematite included quartz points at a pegmatite in Mason County, Texas. I found the the "concave sections" of the points prettying interesting and several other of the points she found had similar features. After some trial and error I realized these two points fit very snuggly together such that they look like a single specimen. The only sign of breakage is towards the bottom. What is the technical term for these type of crystal growth? How common is this type of thing?
16th Jun 2013 21:06 UTCErik Vercammen Expert
Nice find and intriguing intergrowth pattern, but I've never read nor heard a term for this phenomenon.
16th Jun 2013 22:36 UTCDavid Dillman OP
17th Jun 2013 00:33 UTCReiner Mielke Expert
This is very common with quartz and as far as I know there is no technical term for this. They are simply crystals that have grown together, the stepped surface is the contact between the individual crystals.
17th Jun 2013 01:58 UTCJim Bean ๐
I've heard them called keys, as one keys into another. Definitely not a technical term though.
17th Jun 2013 05:17 UTCWayne Corwin ๐
David
Contact points. (the white, or lighter areas) "the "concave sections" "
Between randomaly grown Quartz crystals.
They also have a heavy Iron stain or hematite on the crystals.
Contact points. (the white, or lighter areas) "the "concave sections" "
Between randomaly grown Quartz crystals.
They also have a heavy Iron stain or hematite on the crystals.
20th Jun 2013 01:23 UTCRonald J. Pellar Expert
Their called "intergrowths". :-)
26th Jun 2013 20:20 UTCkatcampbell
It's called twinning- Japan Law twinning, I think.
26th Jun 2013 21:30 UTCBob Harman
For Katcampbell they are NOT Japan law twins!!! NO twinning here that I can see. I agree with the others on this thread that the shown example has just intergrown quartz crystals. CHEERS........BOB
26th Jun 2013 21:58 UTCStephanie Martin
Agree with the others, these are just intergrown crystals. For those who want a quick hit about types of quartz twinning, check out Amir's quartz twinning page:
http://www.quartzpage.de/crs_twins.html
regards,
stephanie :-)
http://www.quartzpage.de/crs_twins.html
regards,
stephanie :-)
26th Jun 2013 22:48 UTCJohan Kjellman Expert
katcampbell Wrote:
-------------------------------------------------------
> It's called twinning- Japan Law twinning, I think.
Big NO for this one.
Please only answer if you know the answer - enough confusion in the world anyway.
cheers
-------------------------------------------------------
> It's called twinning- Japan Law twinning, I think.
Big NO for this one.
Please only answer if you know the answer - enough confusion in the world anyway.
cheers
27th Jun 2013 11:54 UTCDebbie Woolf Manager
Jim Bean Wrote:
-------------------------------------------------------
> I've heard them called keys, as one keys into
> another. Definitely not a technical term though.
Not keys either, a 'key' is the terminated point indentation of another crystal, not that I believe that kinda stuff !
-------------------------------------------------------
> I've heard them called keys, as one keys into
> another. Definitely not a technical term though.
Not keys either, a 'key' is the terminated point indentation of another crystal, not that I believe that kinda stuff !
28th Jun 2013 03:07 UTCJim Bean ๐
Thanks for the correction Debbie! Didn't know there was a metaphysical connection to the term.
28th Jun 2013 04:40 UTCKeith Wood
I've always called them competitive growth contacts. They indicate simultaneous growth. But I'm not sure if there is a more correct term.
28th Jun 2013 15:03 UTCWilliam C. van Laer Expert
To all: this is a contact between two crystals called a re-entrant.
Chris
Chris
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Copyright © mindat.org and the Hudson Institute of Mineralogy 1993-2026, except where stated. Most political location boundaries are ยฉ OpenStreetMap contributors. Mindat.org relies on the contributions of thousands of members and supporters. Founded in 2000 by Jolyon Ralph and Ida Chau.
To cite: Ralph, J., Von Bargen, D., Martynov, P., Zhang, J., Que, X., Prabhu, A., Morrison, S. M., Li, W., Chen, W., & Ma, X. (2025). Mindat.org: The open access mineralogy database to accelerate data-intensive geoscience research. American Mineralogist, 110(6), 833โ844. doi:10.2138/am-2024-9486.
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