W1D3 - Silicate mineral classification-2

New channel Dr. Harel Thomas Petrology: title sample judged 'whole' (This is a structured university-style MOOC course on petrology/mineralogy with nearly every upload being a genuine lectu); 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.