Mineralogy: Lecture 6, Hermann-Mauguin Notation

New channel Kenneth Befus: title sample judged 'whole' (This is a genuine geology/mineralogy teaching channel with structured lecture series, with only an occasional promo or n); passed a second screen for sellers/exam-prep/re-uploads; 2 of 3 sampled transcripts showed teaching, 0 not; every title checked strictly; oEmbed verified.