OR/15/033 Sampling

Shaw, R P. 2015. The Underground Geology of part of the Carrock Tungsten Mine, Caldbeck Fells. British Geological Survey Internal Report, OR/15/033.

The mine is situated in an SSSI and approval for sampling was sought from Natural England. Sampling was restricted to collection of representative loose material. Several suites of samples were collected comprising:

• A limited number of representative host rock samples;
• Tungsten vein samples;
• Lead vein samples;
• Tailings samples; and
• Water samples (x10).

The tailings and water samples were collected at both underground and surface locations and the vein and wall rock samples from loose material, considered to be close to its’ source, from underground locations only. Details of all samples collected are summarised in Appendix 1.

Rock samples

The wall rock samples collected during fieldwork have not yet been studied in detail. They have principally been used to confirm observations/identification of host rocks made during the underground mapping. They are held at the British Geological Survey and are available for future study.

Vein samples

Two sets of vein samples were collected, one representative of the tungsten mineralisation and the other of the ‘lead’ veins. The tungsten vein samples, mainly from the Smith Vein structures, were examined in detail by Tarip (2013) as part of her chemistry MSc dissertation project. This dissertation contains detailed information on the minerals present and their habit based on SEM/BSEM examination of sub-samples.

Water samples

Ten water samples were collected, six from underground locations and four from surface stream courses. The latter were collected from the Grainsgill and Brandy Gill Becks above, below and close to the mine site. The underground samples were collected before any other disturbance of the water to be representative of the main inflows into the mine including that through the tailings stowed into the worked out stopes of the Harding Vein South. Sample locations are shown on Figure 15. The samples were analysed by Tarip (2013) as a part of her MSc project and the results are summarised in Table 1.

Figure 15 Plans of the surface (left) and mine workings (right) showing the approximate locations of water and tailings samples collected in May 2013. Red circles and sample letters are water samples and blue circles and letters are tailings samples. OS base map Ordnance Survey Licence No. 100021290 EUL. Mine plan based on Figure 23 in Cooper and Stanley (1990) with additions surveyed in May 2013 by Warren Allison and the author.

The analytical data show that the levels of arsenic in all of the water samples, including sample C collected from Grainsgill Beck upstream from the mine, site exceed WHO safety limits (10 µg l-1 ) (WHO; 2011) significantly (up to 2339.13 µg kg-1). No other elements exceed the WHO limits.

Table 1 Physical parameters, anionic, cationic and trace element concentrations in surface water and mine drainage samples. See Figure 15 for sample locations. LoD = limit of detection (from Tarip; 2013).

Method	Determinand	Site	Surface stream waters				Mine waters
		Units	A	B	C	J	D	E	F	G	H	I	LoD
Field parameters	T	⁰C	6.20	5.76	6.14	5.60	6.40	5.10	5.10	6.50	6.10	7.69	-
	pH		7.15	7.16	7.39	7.35	7.6	7.06	7.55	7.69	8.07	7.27	-
	EC	µS cm-1	62.30	60.30	105.69	57.80	120.10	101.10	156.50	152.00	145.70	159.30	-
	TDS	µg l-1	31.20	30.10	52.78	28.90	59.60	50.60	78.10	76.10	72.70	79.60	-
IC	F-	µg kg-1	<LoD	<LoD	0.06	<LoD	<LoD	<LoD	<LoD	<LoD	<LoD	<LoD	0.45
	Cl-	µg kg-1	5.69	8.20	5.87	5.93	5.55	5.63	5.52	5.53	4.99	5.87	0.95
	NO3-	µg kg-1	<LoD	2.47	0.70	<LoD	<LoD	<LoD	<LoD	<LoD	<LoD	<LoD	1.79
	SO4-	µg kg-1	5.17	2.99	10.19	3.92	11.98	22.12	22.36	10.39	9.43	10.28	2.44
ICP-OES	Ca	µg kg-1	4.77	4.24	11.49	3.57	16.56	11.92	18.57	17.53	17.89	17.80	0.12
	Fe	µg kg-1	0.31	0.33	0.78	0.28	0.66	4.10	0.41	0.38	0.38	0.64	0.21
	K	µg kg-1	27.12	27.07	27.12	27.20	27.15	27.15	26.89	27.05	26.97	27.41	0.49
	Li	µg kg-1	1.33	1.33	1.32	1.32	1.32	1.31	1.31	1.31	1.32	1.30	0.15
	Mg	µg kg-1	1.87	1.73	3.19	1.47	4.51	2.49	3.73	4.94	4.23	5.60	0.14
	Na	µg kg-1	260.27	259.37	257.05	254.88	257.97	255.73	256.01	256.18	254.62	256.98	4.86
UV-Vis	Fe2+	µg kg-1	0.60	0.61	0.80	0.59	2.37	0.59	0.61	0.60	0.63	0.75	0.09
ICP-MS	Ag	µg kg-1	<LoD	<LoD	<LoD	<LoD	<LoD	<LoD	<LoD	<LoD	<LoD	<LoD	4.56
	As	µg kg-1	309.54	316.71	21.41	409.31	1862.25	2252.27	1598.54	1963.98	1556.90	2339.13	5.93
	Ba	µg kg-1	48.71	41.80	58.09	19.14	38.27	97.71	74.01	34.76	31.57	40.21	6.17
	Bi	µg kg-1	<LoD	<LoD	<LoD	<LoD	<LoD	<LoD	<LoD	<LoD	<LoD	<LoD	6.99
	Cd	µg kg-1	<LoD	<LoD	<LoD	<LoD	<LoD	<LoD	<LoD	<LoD	<LoD	<LoD	5.56
	Co	µg kg-1	<LoD	<LoD	<LoD	<LoD	<LoD	<LoD	<LoD	<LoD	<LoD	<LoD	3.79
	Cr	µg kg-1	5.69	5.41	5.02	5.14	4.74	5.07	4.76	5.41	5.42	4.31	4.11
	Cu	µg kg-1	8.03	5.99	4.22	12.47	6.07	5.99	11.27	7.50	9.77	6.51	3.73
	Hg	µg kg-1	<LoD	<LoD	<LoD	<LoD	<LoD	<LoD	<LoD	<LoD	<LoD	<LoD	4.16
	Mo	µg kg-1	<LoD	<LoD	<LoD	<LoD	8.34	<LoD	23.26	8.52	<LoD	8.76	4.23
	Ni	µg kg-1	7.10	8.66	5.44	5.04	9.56	15.61	11.32	10.00	9.06	12.18	4.58
	Pb	µg kg-1	<LoD	<LoD	<LoD	<LoD	<LoD	<LoD	<LoD	<LoD	<LoD	<LoD	6.31
	Sb	µg kg-1	<LoD	<LoD	<LoD	<LoD	<LoD	<LoD	6.29	<LoD	<LoD	<LoD	5.06
	Se	µg kg-1	<LoD	<LoD	<LoD	<LoD	<LoD	<LoD	<LoD	<LoD	<LoD	<LoD	12.44
	Sn	µg kg-1	<LoD	<LoD	<LoD	<LoD	<LoD	<LoD	<LoD	<LoD	<LoD	<LoD	4.43
	Sr	µg kg-1	83.34	73.16	57.46	76.29	151.50	69.33	159.45	165.37	174.05	163.33	5.02
	Th	µg kg-1	<LoD	<LoD	<LoD	<LoD	<LoD	<LoD	<LoD	<LoD	<LoD	<LoD	1.50
	Ti	µg kg-1	<LoD	<LoD	<LoD	4.68	3.99	<LoD	4.60	5.85	7.37	7.42	3.80
	U	µg kg-1	<LoD	<LoD	<LoD	<LoD	<LoD	<LoD	3.36	<LoD	<LoD	<LoD	2.78
	W	µg kg-1	8.12	7.31	<LoD	18.43	29.68	78.34	103.28	28.56	69.84	47.15	3.92
	Zn	µg kg-1	56.15	49.39	23.64	57.22	275.93	309.52	153.52	276.59	298.35	288.97	13.26

Tailings samples

There are several surface dumps of tailings arising from the dressing of tungsten during the different phases of mine operation at the site resulting from the extraction of tungsten minerals from the mined ores. These include early stopes that were backfilled during the last phase of mining for disctete disposal within the national park. A suite of seven tailings samples were collected, three of these were from surface tips and the remainder from the floor of the Harding Vein workings where they have accumulated as a result of water flows through the stowed waste in the old stopes on this vein. These samples have not been analysed and are held at the British Geological Survey where they are available for future study.