Far as I understand, twins may or may not have macroscopically recognizable features. Macroscopic (and microscopic) features like face angles, reaction on etching, polarization of light, etc. can sometimes indicate twinning for at least a subset of cases, e.g. in diamond, some forms of quartz, etc. (see Hahn and Klapper, "Twinning of Crystals" in the International Tables for Crystallography).
Best wishes, Navdeep https://scholar.google.de/citations?user=ZqU1AE0AAAAJ --- On 17.03.21 11:12, Ana Luísa Moreira de Carvalho wrote: > Just a short note on this: I often see colleagues using the word > “twinning" when referring to a crystal that is actually multiple (not > single). > > I think much confusion arises from this. For me, a twin crystal is the > one that looks single under the microscope and only intensity statistics > reveal that the diffraction comes from more than one crystal. > > If a crystal looks multiple, i do not call it a twin. Am i being too > meticulous on this? > Thanks! > >> On 16 Mar 2021, at 13:31, Eleanor Dodson >> <[email protected] >> <mailto:[email protected]>> wrote: >> >> You usually detect twinning most reliably from the intensity >> statistics - CCP4I2 and Xtriage report those.. >> Eleanor >> >> On Tue, 16 Mar 2021 at 07:31, Marina Gárdonyi >> <[email protected] >> <mailto:[email protected]>> wrote: >> >> Dear all, >> >> thanks to all who helped me solving the question. You sent me a >> lot of >> comments and information I have not taken into account. >> After reading all the answers, I have come to the conclusion that >> the >> spots that are very close to each other come from the long cell axis >> (57-57-160) and that twinning can probably not be seen in my case. I >> should have mentioned that the diffraction images came from an >> in-house x-ray machine, recorded with a 0.5 degree rotation range. >> >> Thank you all again! >> >> Kind regards, >> Marina >> >> -- >> Marina Gárdonyi >> >> PhD Student, Research Group Professor Dr. Klebe >> >> Department of Pharmaceutical Chemistry >> >> Philipps-University Marburg >> >> Marbacher Weg 6, 35032 Marburg, Germany >> >> Phone: +49 6421 28 21392 >> >> E-Mail: [email protected] >> <mailto:[email protected]> >> >> http://www.agklebe.de/ <http://www.agklebe.de/> >> >> ######################################################################## >> >> To unsubscribe from the CCP4BB list, click the following link: >> https://www.jiscmail.ac.uk/cgi-bin/WA-JISC.exe?SUBED1=CCP4BB&A=1 >> <https://www.jiscmail.ac.uk/cgi-bin/WA-JISC.exe?SUBED1=CCP4BB&A=1> >> >> This message was issued to members of www.jiscmail.ac.uk/CCP4BB >> <http://www.jiscmail.ac.uk/CCP4BB>, a mailing list hosted by >> www.jiscmail.ac.uk <http://www.jiscmail.ac.uk/>, terms & >> conditions are available at >> https://www.jiscmail.ac.uk/policyandsecurity/ >> <https://www.jiscmail.ac.uk/policyandsecurity/> >> >> >> ------------------------------------------------------------------------ >> >> To unsubscribe from the CCP4BB list, click the following link: >> https://www.jiscmail.ac.uk/cgi-bin/WA-JISC.exe?SUBED1=CCP4BB&A=1 >> <https://www.jiscmail.ac.uk/cgi-bin/WA-JISC.exe?SUBED1=CCP4BB&A=1> >> > > > ------------------------------------------------------------------------ > > To unsubscribe from the CCP4BB list, click the following link: > https://www.jiscmail.ac.uk/cgi-bin/WA-JISC.exe?SUBED1=CCP4BB&A=1 > <https://www.jiscmail.ac.uk/cgi-bin/WA-JISC.exe?SUBED1=CCP4BB&A=1> > ######################################################################## To unsubscribe from the CCP4BB list, click the following link: https://www.jiscmail.ac.uk/cgi-bin/WA-JISC.exe?SUBED1=CCP4BB&A=1 This message was issued to members of www.jiscmail.ac.uk/CCP4BB, a mailing list hosted by www.jiscmail.ac.uk, terms & conditions are available at https://www.jiscmail.ac.uk/policyandsecurity/
