Zona Alterasi Hidrotermal Berdasarkan Analisis Petrografi dan X-ray Diffraction (XRD) di Kawah Tapal Kuda, Gunungapi Papandayan, Garut, Jawa Barat = Hydrothermal Alteration Zone Based on Petrographic and X- Ray Diffraction (XRD) Analysis in Horseshoe Crater, Papandayan Volcano, Garut, West Java