Sample number



1, 2, 20

Aplite granite with highly crashed rocks affected by alteration

Granite rock fragments composed of quartz, feldspar, and biotite. Highly fractured crystals of feldspar, quartz, hornblende and epidote. Hornblende occurs in clots giving the rock a mottled appearance. The cemented material consists of calcite and very fine grains of quartz or cryptocrystalline. Quartz was partially metamorphosed to quartzite.

3, 26

Alteration granite, fine to medium grain size, mineral composition quartz, feldspar and biotite, with calcite veins associated in the alteration zone

Calcite minerals contain cavities filled with fibrous quartz and opaque minerals. Calcite shows polysynthetic twinning and two cleavage sets (rhomb cleavage). Silica occurs as cryptocrystalline fibrous chalcedony and fine-grains filled the fractures and spaces or voids. Micrographic textures are visible. Iron oxides occur surrounding the voids or separated along the fractures.

4, 6, 7, 8, 9, 10, 11, 34, 60

The alteration zone includes quartz veins with highly crashed rocks

The major textures evident are equigranular, interstitial perthitic and poikilitic. Quartz occurs as anhedral and highly fractured crystals, filling up the spaces between the plagioclase crystals. Feldspar occurs as plagioclase, a major component and a few percent of perthite with perthitic texture. More than 40% is plagioclase found as euhedral and subhedral prisms showing zoning and polysynthetic twinning. It is highly weathered and altered to calcite and sericite. Biotite is rare and highly weathered having been altered to iron oxides.

12, 13, 14, 15, 16, 17, 18, 19, 23, 29, 30, 31, 33

Thin Quartz veins (2 - 5 cm in thickness), showing a high degree of alteration and crashed rocks, and trace minerals, like Cu and Pb

The major texture is equigranular and spherulitic. It consists of euhedral elongated crystals of quartz and orthoclase as the major minerals due to the intergrowth between quartz and feldspar like a sheaf form. The slide shows cryptocrystalline silica as a banded rock from the veins, thin veins of cryptocrystalline and spherulitic chalcedony associated with sericite and calcite, fine-grained quartz and finally cryptocrystalline and fibrous chalcedony associated with sericite. A few crystals of orthoclase partially altered and sericite. Iron oxides occur as accessories as very fine aggregates.


Applite granite with green color and alteration

The slide shows felsitic rock composed of feldspar and quartz crystals. The feldspars are altered to sericite and kaolin minerals. Biotite occurs as rare mineral and is altered to chlorite.

22, 59

Quartz veins with the secondary green color of the minerals

Graphic texture is observed. The biotite xenocrysts are partially altered to chlorite and iron oxides. Iron oxides and black spots occur as accessories and separated randomly in the groundmass.

24, 32, 27, 28

Basaltic dyke cutting the granite host rocks, with quartz veins

This slide shows two types of rock composition, the first being andesite rock. It consists of feldspar and glass. The feldspar (plagioclase) occurs as small laths and shows twinning and zoning. It is predominantly trachytic in texture. It contains black materials which could be volcanic glass or opaque minerals. The second type comprises chalcedony veins cutting the andesite rock. Spherulitic texture is predominant in the dyke and consists of a dense mass of very intergrown quartz and alkali feldspar (orthoclase) needles, radiating from a common nucleus. These spherulites are followed by fine-grained quartz presenting a drusy structure followed by calcite mineral in the middle (forming bands). This dyke is rich in opaque and fine accumulated band-like aggregates separated from the beginning of the dyke to its end.


Granodiorite, composite of mafic minerals feldspar, Biotite and hornblende

Granular, consertal and poikilitic textures predominate. Anhedral and highly fractured quartz crystals comprise about 30%. Feldspar includes both the orthoclase and plagioclase forms. Plagioclase constitutes more than 45% and occurs as euhedral to subhedral prisms showing zoning and polysynthetic twinning. It has been highly weathered and altered to clay and sericite. Biotite occurs in about 10% of highly weathered rock, altered to chlorite-like masses.