Slate deposits of Nepal and India

The description of the slate in Nepal follows Neupane and Paudel from 2012: Both mention that slate have been used for several years. They state numerous studies which describe various slate deposits in the Lesser Himalaya Regions. There is supposed to be a very good slate at Bandipur area, Tanahu. Other were reported in Singchyang Garhi (Udayapur), Gairimudi (Kavre), Chautara area (Sidhupalchok), Bigu (Dolakha), Gaighat (Tanahu), Kelodighat (Syangja), Ranipauwa (Nuwakot) or Gajuri (Dhading). Other indicate 31 locations of slate occurrences in Nepal. Nevertheless, comprehensive investigation for a possible exploitation are still lacking.

Both authors investigated the slate deposit in the Tharpu area within the Tanahu district which is well-known for slate mining in western Nepal.
This area is situated in the Midland zone of the Lesser Himalaya. The intensely folded rocks and occur in a roughly W-E trending syncline and two small anticlines. They observed the slate deposits at the locations of Seratar, Phapardanda and Chipliswara where slate is being presently mined and used for roofing.

The slates of Seratar and Phapardanda belong to the Nourpul Formation, comprising alternating bands of grey slate and grey, pink and green quartzites of about 1,100 m thickness. The slates at Chipliswara belong to the Benighat Slate, comprising alternating bands of grey slate, black slate and grey quartzite. Slate is being mined in the lower part of the 3,000 m thick Benighat Slate.

Slates are known in the region of Markapur-Cumbum (state Andhra Pradesh) in the south of India. This slates occur at the easteren part of the crescent-shaped Cuddapah basin. The following informationen steam from the unpublished report of Prof. Joachim Hofmann.

The Cuddapah basin lies on the Dharwar craton and developed during the Proterozoic. The slates belong to the Nallamalai Series of the Middle Proterozoic Cuddapah systems and evolved during tectonic events about 1.4 Ma ago. The cleavage plane is parallel to the bedding. The slates have a thickness between 30-40 m (98-131 ft.) and the strike is roughly N-S with a steep dip. They occur in the upper most part of the Adda Hill, which is ridge with a length of several kilometer and a hight between 50-100 m (164-328 ft.).

The slates are exposed by several quarries over a total length of over 5 km (3.3 mi.).

In the lower part the minable slates comprise grey to yellowish or grey-green psammitic slates, respectively. This is followed by black slates and black rusty slates. The dark slates show a relative homogeneous petrography with a fine lamination, containing grey carbonatic-sandy material. In the upper part different grey slates can be found which can show a homogeneous as well spotted reddish colouring.

Pictures

Move mouse over thumb to enlarge. The photographs are from Prof. Joachim Hofmann from 1997

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  Fig. 1 The exploitation is carried out in a simple manner by hand.

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  Fig. 2 Slate heaps

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  Fig. 3 Steep slates

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  Fig. 4 Steep slates

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  Fig. 5 Crane to haul out slate blocks

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  Fig. 6 Stock of slate shingles

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  Fig. 7 Stock of slate shingles

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  Fig. 8 Stock of slate shingles

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  Fig. 9 Bedding and cleavage plane run parallel.

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  Fig. 10 Bedding and cleavage plane run parallel.