Exploring Minerals In Nepal

Siddhi B. Ranjitkar

Mid hills of Nepal is not only fertile for agriculture but also for hosting minerals particularly copper, lead and zinc. All along the mid hills, we can see many ancient workings of cooper and some of lead but not of zinc, as it is usually associated with lead so not visible to our regular eyes. The Government of Nepal approaches the UNDP for exploring copper, lead and zinc in the mid hills of Nepal, and together with the UNDP forms a HMG/UNDP Mineral Exploration Project for exploring copper, lead and zinc in mid 1970s and completes it in mid 1980s. This project is one of the most successful ones in Nepal.

The Government of Nepal forms a Mineral Exploration Development Board for running the HMG/UNDP Mineral Exploration Project independently. The Board has all sorts of authorities for making decisions on running the HMG/UNDP Mineral Exploration Project efficiently and correctly.

The objective of the HMG/UNDP Mineral Exploration Project is for Nepalis to assimilate the technique of geochemical exploration, of analyzing stream sediment and soil samples for detecting elements in parts per millions and billions, and of using photos for geological survey. So, the project has mainly focused on these three subject matters.

UNDP has provided all sorts of logistical supports, high quality experts and vehicles for running the project efficiently. The Government of Nepal has provided office space, the project manager, Nepalese professional counterparts and their salaries. About ten Nepalese geochemists have worked with three expatriate expert geochemists including the expatriate project manager. One Nepalese counterpart geologist is attached to an expert photo-geologist to set up a photo-geological lab and run photo-geological mapping. Two highly qualified Nepalese chemists are also attached to an expatriate expert chemist to set up a chemical lab that can conduct chemical analysis of stream sediment and soil samples brought in thousands.

The project has the joint management of a Nepalese manager and a counterpart expatriate manager. Following the Nepalese government rules and regulations, the Nepalese project manager takes care of the management of making sure that the project has no shortage of materials and manpower the Nepalese side is supposed to provide. Similarly, the expatriate project manager takes care of the UNDP side of logistical management to providing the project with experts for smoothly running the project to achieve its goals and objectives.

The Nepalese professionals have worked with the expatriate professionals in teams. The project has a number of geo-chemists working independently and in a team with the expatriate professionals but the photo-geology has a single team of a Nepalese professional and an expatriate professional, and the entire population of the chemical section has worked with the expatriate chemist as a team to provide the geochemists with the support for chemical analysis of stream sediment and soil samples.

Professionals such as geochemists, photo-geologists and chemists hold their regular independent weekly meetings to discuss their problems and prospective events. They also hold independent regular meetings with the joint project management. Sometimes the joint project management holds a meeting of all professionals whenever the need for such a meeting arises.

Such meetings have become the arena for the close interactions between the Nepalese and expatriate professionals and have contributed to the assimilation of knowledge, skills and techniques of the respective field by the Nepalese professionals from the expatriate expert counterpart professionals. The best transfer of knowledge and skills has occurred while Nepalese and expatriate professionals working together in the field. The mid hills of Nepal have become the laboratory for the Nepalese geochemists to assimilate the knowledge and skills of geo-chemical exploration. Photo-geology lab has become the place for the Nepalese photo-geologist to assimilate the skills in photo-geology. Similarly, the chemical lab has become the place for assimilating skills in chemical analysis of stream sediment and soil samples for Nepalese chemists.

In the photo-geological lab, photo-geologists have worked on thousands of aerial photos acquired from the survey department to prepare geological maps. After completing geological maps studying the photos, they go to the field to check their findings.

Nepalese chemists have worked together with the expatriate professionals on analyzing stream sediment and soil samples to detect mineral contents in parts per millions and billions. Professional chemists have been the first to assimilate knowledge and skills in chemical analysis of stream sediment and soil samples. So, the expatriate expert chemist has departed turning over all the responsibilities for chemical analysis to the Nepalese counterpart professionals after a few years.

The project management has first identified the background content of copper, lead and zinc in stream sediment and soil samples and some rocks of mid hills in Nepal in parts per millions and billions. The project has called them background values mean you will find such contents of minerals in stream sediments, soils and rocks found elsewhere in the mid hills in Nepal.

The project has started the geochemical exploration for copper, lead and zinc with the stream sediment samples. Geochemists collect stream sediment samples and then submit these samples to the chemical lab with the request for analyzing them for copper, lead and zinc. After receiving the chemical analysis of stream sediment samples, the concerned geochemist plots the results on the one-inch equals to one-mile maps for the three minerals in question. Then, each geochemist prepares a report on the findings of his field trip and submits it to the joint project management.

The project management has set six digit numbers for stream sediment samples and for soil samples considering the number of samples the project professionals will collect during the project life. These numbers in blocks are allocated to Nepalese professionals for numbering the samples they collect in the field.

Each geo-chemist has received a block of six-digit numbers for numbering stream sediment samples. He can use only those numbers for the samples he collects in the field. Before going to a field trip, each geochemist serially prints the numbers allocated to him on the number of paper bags of size 2” x 6” required for him to collect samples in one field trip he is assigned to. He traces the streams of the area of his field trip from the one-inch equal to one-mile maps provided by the Survey Department. He makes an ammonia print of the traced-out map and takes the map with him to the field to locate the stream samples on the map.

In the field, the geochemist collects stream sediment samples digging with his hand from each stream he is assigned to collect. He collects one stream sediment sample a few meters above the mouth of each stream so that the waters of the river has not diluted the sediment, and from the middle of the stream so that the sample has equal chance of getting sediments from both sides of its watershed. He puts the sample in the pre-numbered paper bag, and notes the number of the sample on the map. The river becomes the stem of a tree and streams its branches. The geochemist collects stream sediment samples from the branches not the stem.

A technical assistant and non-technical assistants go with each geochemist to the field for helping him. The technical assistant helps him to collect the stream sediment, and non-technical assistants help him to prepare samples and provide him with other support services.

Non-technical assistants dry the stream sample on the sun. Then, they carefully put the samples through 200-mesh sieve. They put back the sieved samples to the respective sample bags. Each sample will be about 200 grams. In such a way they don’t have to bring the unwanted material to the office.

The geochemist is also to record the rock exposure and the geology of the area as much as possible. Such a simple preliminary geological map helps to understand the possible mineralization in the areas.

As soon as the geochemist arrives in the office in Kathmandu, he briefs the joint project management about the field trip in an informal meeting. He submits the samples to the chemical lab for chemical analysis of the samples for copper, lead, and zinc. At the same time, he prepares a map for plotting the chemical results of the samples.

The Chemical lab prepares the reports on the chemical analysis of stream sediment samples in triplicate. It submits the first copy to the joint project management, the second copy to the concerned geochemist and keeps the third copy in the archives of the lab.

The geochemist plots the results of the chemical analysis of the samples for copper, lead, and zinc in three separate maps: one for copper, another for lead and the third for zinc. He draws values higher than the background values with three different thick lines that represent high, mid high and low high.

Thickness of each stream represents the value of the result of chemical analysis of the stream sediment sample the geochemist has collected from it. The project management has classified the results of stream sediments higher than background values into three categories: high, mid high and low high. Following the classification of the chemical analysis results of stream sediment samples, each geochemist draws the streams by different thicknesses of lines proportional to the results. So, each stream is of either of simple line of background value or thick line of high value, or middle thick line of mid value or of low thick of low value. For drawing the quick attention of the project management to the high, mid and low high values, each geochemist colors the high values with red, mid high with yellow and the low high with green. These high values are called anomalies. The project management gives the first priority to the red color streams for the follow-on next geochemical exploration fieldwork.

Following the stream-sediment-sampling process, the project has already located a number of anomalies that are possible mineralization in a large area. The project needs to narrow down the area of each mineralization so that it can reach the mineral deposit. The next follow-on work is the soil sampling on the ridges and spurs from where the streams that have shown the high values of mineral content have drawn the rainwater.

Depending on the size and intensity of anomalies, the project management decides which of the so many anomalies to take up for the follow-on ridge-and-spur soil sampling work. The large anomalies with high intensity of anomalous values get the first attention of the project management. Then, the project management assigns the project geochemists to hold the soil samplings on the first target anomalies.

For soil sampling, geochemists use simple compass, a 30-meter-long nylon rope for measuring the distance between two samples and about a half-meter long crowbar for digging a hole in the ground. As in the case of stream sediment sampling, geochemists take a number of pre-numbered paper sample bags required for the number of soils to be collected in the field.

In the field, a geochemist responsible for holding the soil sampling on the ridge and spurs sets his camp at the middle of the ridge keeping the spurs on both sides at an equidistant. A ridge is the hill range from where spurs branch out on both sides of the hill range.

The geochemist finds a large stone or a tree or something else that does not disappear in the near future, and sets it as a base-point from where he starts sampling the soil on the ridge. He marks it with red paint so that anybody can go back to the area and verify the sample if a need for it arises. He also paints rock exposures and large trees elsewhere found in the sampling area with red paint stating the field date and the soil sampling in the area for the future references.

The geochemist identifies the first place of taking soil sample on the ridge, and calls it a base-point. At this place, a non-technical staff digs a small hole through which a hand can pass in on the ground to a 30-cm deep. Then, he takes the soil sample from the 30-cm deep and puts it in the pre-numbered paper sample bag and seals it. Thereafter, the geochemist stands on the place the soil sample has been taken and holds one end of the 30-meter-long nylon rope and sends the assistant holding another end of the rope to the next place of sampling. He measures the direction of the next position of the soil sampling. The assistant digs a 30-cm deep hole with an iron bar at the new position to take another sample. This soil sampling process continues to the end of the ridge and the same process is followed for the soil sampling on the spurs.

The project management has identified 30 meter as the minimum sample interval on the ridges and spurs to define the anomaly detected by the stream sediment samples. It will give the required number of soil samples to delineate the size of an anomaly. The project calls it still an anomaly, as it is only the surface delineation of a mineralization that becomes a mineral deposit in the later follow-on exploration.

The project management has also set the 30-cm as the maximum depth required for taking soil samples. At this depth, you are sure to reach the in-situ soil. Reaching to this depth, you avoid all the debris and organic materials found on the surfaces of hills.

As in the case of the stream sediment samples, the assistants dries all the soil samples on the sun and then passes them through the 200-mesh sieve and brings those samples to Kathmandu for chemical analysis. He submits the samples to the chemical lab for the chemical analysis for the mineral the follow-on soil sampling has been done.

The geochemist briefs the joint project management on the field trip. He reports on the problems and prospects of the anomaly, and the preliminary geology of the area including the physical features.

The geochemist prepares a map of the ridge and spurs from where he has collected samples plotting the directions of soil samples he has taken in the field. He also plots the locations of soil sample on the map. As soon as, he receives the results of the chemical analysis of the soil samples he has collected, he plots the result of each sample on the map, and reads the results on the map, and then he draws the anomaly of the soil samples. The soil sampling has reduced anomaly to a considerably small size in the area, and has been closer to the mineral deposit.

The joint project management discusses an anomaly in the meeting of all geochemists to see whether it needs follow-on actions or not. Along with a brief technical report on his field trip, the geochemist submits the results of the ridge and spur soil sampling to the joint project management. Depending on the size of the anomaly, the project management sets its priority for a review and for follow-on actions. If the project management sees it deserve additional actions then it calls the meeting of all geochemists to discuss the anomaly. The concerned geochemist presents his findings and the justifications for additional follow-on actions if he thinks necessary. If the anomaly does not warrant any additional action, it goes to the archives.

If the anomaly deserves additional actions then the project management assigns the concerned geochemist for follow-on soil sampling. This is called a detailed soil sampling. The project is gradually reaching to the mineral deposit. So, the joint project management sends an expatriate expert geologist to ascertain the geology of the area and to see the possibility of finding a mineral deposit of any economic size. The geochemist follows the same sampling interval for the detailed soil sampling.

If the geochemist finds a reasonably consistent anomaly that promises possibly an economically viable mineral deposit then the project management launches follow-on exploration by drilling into the underground mineralization for rock sampling to identify a size and intensity of the mineralization. Before launching such an expensive exploration of a mineral deposit, the joint project management seriously discusses the findings of the mineralization with all the geochemists working in the project to see the possibility of finding an economically viable mineral deposit.

In the course of the mineral exploration, the project has collected thousands of steam sediment and soil samples, and analyze them for copper, lead and zinc, and has stored the reports of the chemical analysis, and the reports of the field trips and on the various anomalies for the future references in the archives of the Department of Mines and Geology.

If the Department of Mines and Geology or any interesting company or anybody wants to ascertain any other minerals, any of the agencies or s/he can retrieve the stream sediment and soil samples and can do the chemical analysis for any minerals.

The project has been successful to transfer the knowledge and skills in geochemical exploration from the expatriate experts to the Nepalese professional counterparts thus achieving the objectives of the project. However, it has been short of achieving the goal of finding an economic mineral deposit to the disappointment of the joint project management.

Ancient mineral explorers have already found most of the copper deposits identified by the project, and have even worked out even a minor deposit for extracting copper. They have done so, as one of the rulers called Prithvi Narayan Shah has forced the people of smith caste to pay tax in metals so they have to search mineral deposits and work out any size of minerals, and extract metal by the primitive method of smelting and submit the metal to the ruler.

The hunters of a copper mineral have used the method of locating green residue elsewhere in the hills for finding a copper deposit. One of the copper minerals has a green color. So, they had been successful to identify copper deposits following the green sediments in the hills.

Once they have found such a green residue, they have simply followed it to reach the mineralization. No matter how small the mineralization is they have worked it out for most probably survival. They have dug holes of sizes just enough for a man to crawl in and cut the mineral and bring it out in a wicker basket. The project geochemists have found many such past workings while in the field trips. Some of them are quite impressive. The ancient miners have dug a main small hole following the mineral deposit and then many small branch holes from the main hole.

They have crushed the ores manually and then extracted metal from the ores smelting it in the crudest way leaving high percentage of metal in the waste product called slag.

August 20, 2010

Note:     HMG stands for His Majesty’s Government
    UNDP stands for United Nations Development Program