Studi karakteristik mineralisasi timah primer menggunakan analisis XRD, XRF, petrografi, dan mineragrafi di Parit Tiga, Kabupaten Bangka Barat, Kepulauan Bangka Belitung = Study of characteristics of primary tin mineralization using XRD, XRF, petrographic, and mineragraphic analysis in Parit Tiga, West Bangka Regency, Bangka Belitung Islands