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Building and Decorative Stones in Yemen

5-1 Marble:  

 Marble1There are two types of marble rocks in Yemen; the first results from regional metamorphism of Jurassic limestone in contact with volcanic rocks. The second type outcrops as large bodies in Precambrian rocks. The occurrences of the marble in Yemen are concentrated in the governorates of Sana’a, Marib, Taiz, Hajjah, Shabwah and Abyan. Marble is the most promising building stone export resource in Yemen. Among the various sorts of marbles, the black, white and grey marble is by far the most abundant, followed by white - light grey fractured marble. Most of the reserve consists largely of marble that is light grey in color with some occurrence of yellow, reddish and greenish variations, but with limited reserves. For this reason, most of the deeper green and red colored marbles popular for decorative purposes are imported. The marble deposits are heavy rocks with medium specific gravity ranging between 2.08 and 2.87, little porous and resistance to compressive strength ranging between 260 and 1130 kg/cm2, with little absorption ranging between 0.04 and 4.42%. The total reserves for the marble rocks in Yemen are estimated to be about 180 million cubic meters.
أطلس أحجار البناء و الزينة في اليمن

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5-2 Granite and Gabbro

Granite1Granite rocks are divided into two types depending on the age of their formation.  Precambrian granite rocks outcrop in two main areas, whilst Tertiary Granite rocks are found in the Ta’iz and Bajil zones. The Tertiary granites generally have a medium-grained texture and grey color. Gabbroic rocks are found within Precambrian basement rocks and as Tertiary intrusive. The occurrences of the granitic and gabbroic rocks are found in the governorates of Al-Bayda, Al-Jawf, Marib, Shabwah, Sadah, Abyan, Hajjah, Al-Hudaidah and Lahj. They are heavy rocks with high specific gravity ranging between 2.16 and 2.95, little porous and resistance to compressive strength ranging between 423 and 2024 kg/cm2, with little absorption ranging between 0.05 and 2.63%. The total reserves for the granitic and gabbroic rocks in Yemen are estimated to be about 2.7 billion cubic meters.

5-3 Carbonate Rocks

Limestone products currently used cover a wide range of extraordinarily attractive limestone with locally distinctive fossils. The occurrences of the limestone are concentrated in the northern and eastern Yemen, in the governorates of Sana’a, Amran, Sadah, Marib, Hadramout, Abyan, Lahj, Shabwah and Al-Maharah.
The chemical and physico-mechnical analysis indicate that the Jurassic limestone rocks can be used as building stone in raw state and as decorative stone as polished plates. They are heavy rocks with medium specific gravity ranging between 1.9 and 2.86, little porous and resistance to compressive strength ranging between 234 and 1520 kg/cm2, with acceptable absorption ranging between 0.04 and 9.05%. The total reserves for the limestone rocks in Yemen are estimated to be about 5.3 billion cubic meters.

limest1In some places of Yemen water from thermal sources (which formed at the end of volcanic activity) dissolved CaCO3 from Jurassic limestones and redeposited them not far away of primary source forming some travertine deposits and of limy tuff. The travertine rocks were discovered in the governorates of Sana’a, Ibb, and Al-Dhali’. Pertographically, the travertine rocks are very fine granulation and beige, yellow-brown color, crystalline granular structure, compact texture, with rare vacuoles and irregular break. They are heavy rocks with medium specific gravity ranging between 2.19 and 2.50 and resistance to compressive strength ranging between 250 and 800 kg/cm2, with acceptable absorption ranging between 2.30 and 5.90%. The total reserves for the travertine rocks in Yemen are estimated to be about 2.5 million cubic meters.

 5-4 Tuff and Ignimbrite 

 Tuff1The tuff is the general term for rock formed of pyroclastic material, whereas the ignimbrite is identical to tuff in formation, but is specifically rock formed by widespread deposition and consolidation of volcanic ash flows. These rocks are especially preferred for building in Yemen due to its variety of bright colors. The colors available are yellow, green, red, brown, and grey; on the whole, pale colors dominate. The representative and most preferred tuff dimension stone is greenish in color, with some being plain and some with flake patterns.

The tuff and Ignimbrite rocks are characterized by variety of attractive colors, easy Shaped, cheap in price, and the technical specifications was good, where it is characterized by low specific gravity ranging between 1.53 and 2.96 and resistance to compressive strength ranging between 170 and 1160 kg/cm2, with acceptable absorption ranging between 0.38 and 19.41%, in addition to distinguish lightweight and characteristics of high thermal and sound insulation. According to these specifications, these rocks are s located within the required specifications with the exception of the world specification. The total reserves for the tuff and ignimbrite rocks in Yemen are estimated to be about 343 million cubic meters.

5-5 basalt:

Baslt1Tertiary basalts volcanic rocks are developed as dykes crossing basement rocks, the Jurassic and Cretaceous deposits and as interstratified flows with tuffs and ignimbrites in equal shares. Quaternary basalts appear as flows and volcanic cones. In Yemen there were identified many occurrences of compact and vesicular basalts. Basalt stone is used for framing doors and windows as well as external decoration. The total reserves for the basaltic rocks in Yemen are estimated to be about 142 million cubic meters.

Compact basaltic rocks are black, gray, black-greenish colored, generally massive with aphanitic structure. They are sporadically exploited in a medium quarry opened in some localities. Compact basalts are used as building stone for house foundations. Intensely fissured basalts are used as broken stone (aggregates) to prepare concretes instead of river gravel, to make some elements for buildings of some wails and for the road infrastructure. The occurrences of the compact basalt occur within the western highlands of Yemen, in Sana’a Dhamar, Ibb and Taiz governorates. The compact basaltic rocks are heavy rocks with specific gravity ranging between 2.00 to 3.01, very low absorbent, very low porous, with high resistance at compression in dry state ranging between 870 to 2200 kg/cm2, resistant at frost-thaw, low resistant at mechanic shock and with middle wear.

Vesicular basaltic rocks are black, gray colored, generally massive with scoriceous structure. They are sporadically exploited in a medium quarry opened in some localities. Vesicular basalts are used as shaped decorative stone with ornamental role in dwellings. The occurrences of the vesicular basalt occur within Quaternary volcanic fields (Sana’a-Amran, Dhamar-Rada’, Marib-Serwah, Shuqrah and Bir Ali). The vesicular basaltic rocks are middle heavy rocks with specific gravity ranging between 1.92 to 2.64, low absorbent, porous, with middle resistance at compression in dry state ranging between 178 to 380 kg/cm2, low resistant at frost-thaw, low resistant at mechanic shock and with medium wear.

Mineral Res. Building and Decorative Stones in Yemen