Alteration Type

DI SUSUN OLEH :KURNIA SETIAWAN WIDANA

NIM : 22010002

MAGISTER TEKNIK GEOLOGIINSTITUT TEKNOLOGI BANDUNG

2010

TUGASALTERASI BATUAN

TIPE-TIPE ALTERASI DAN KENAMPAKAN SAYATAN TIPIS

ALTERATION TYPE

MINERAL TYPES THIN SECTION PHOTOMICROGRAPH

ARGILLIC Kaolin, Montmorillonite, Quartz, Cristobalite, Pyrite,

Calcite, Chalcedony, Zeolite, Adularia

Cristobalite

Zeolite

The oval feature in this photomicrograph is an amygdule: a formerly open vesicle which has been filled with a secondary

mineral(s) precipitated from low-T ground waters which have penetrated into the

rock. In this case, the amygdule is probably filled with a zeolite mineral.

Clay Mineral

Plagioclase altered to clay mineral (kaoline/montmorillonite)

Cristobalite

Opal

Opal

Cristobalite

ALTERATION TYPE

MINERAL TYPES THIN SECTION PHOTOMICROGRAPHS

ADVANCE ARGILLIC

Kaolin, Pyrophyllite, Dickite, Alunite,

Quartz, Topaz, Tourmaline

ALTERATION TYPE

MINERAL TYPES THIN SECTION PHOTOMICROGRAPHS

POTASSIC K-Feldspar, Biotite, Sericite, Chlorite,

Quartz, Magnetite, Hematite, Anhydrite,

Albite, Epidote, Actinolite

Biotite

In this photomicrograph, euhedral to subhedral biotite and plagioclase crystals are

surrounded by optically-continuous, gray-colored K-

feldspar.

Chlorite replacing Biotite

In this photo, a large "book" of

red-brown biotite is partially replaced by green chlorite.

ALTERATION TYPE

MINERAL TYPES THIN SECTION PHOTOMICROGRAPHS

PHYLLIC/SERICITIC

Sericite, Quartz, Chlorite, Pyrite

Pyrite (reflected light microsope)

PyPy

ALTERATION TYPE

MINERAL TYPES THIN SECTION PHOTOMICROGRAPHS

PROPYLITIC Chlorite, Epidote, Prehnite, Actinolite, Clinozoisite, Calcite,

Zoisite, Albite.

Actinolite

Low to medium grade amphibolite consisting essentailly of actinolite-tremolite. The large grain in the centre of the image displays two cleavages

which intersect at 56 - 124°.Field of view 2.7 mm, plane light