North Carolina Geological and Economic Survey
Alleghany and Ashe Counties, North Carolina
Bulletin No. 32
Magnetic Iron Ores of East Tennessee and Western North Carolina
by W. S. Bayley, Geologist
Prepared by North Carolina Geological and Economic Survey
Tennessee Geological Survey
as a joint report
In cooperation with the
United States Geological Survey
Mines and Prospects in Siliceous Magnetites
Alleghany and Ashe Counties, N.C.
The silicous magnetities of Ashe County were used as early as 1802 in Catalan forges and the iron produced was shipped as far as Charleston, S.C., where it enjoyed an enviable reputation. The ores were used locally as late as 1887, until improved transportation facilities allowed cheaper iron to enter the county, and drive out the better and more costly metal. During the war between the States the iron was used in the manufacture of gun barrels. Since 1887 the mines have for the most part lain idle because of the difficulty of transportation, but the building of the Virginia-Carolina Railroad in 1914 opened up a portion of the county and during the past few years a little ore has been shipped from deposits near Lansing. In 1922 no mines were operating.
The siliceous magnetites of the county have been described as occurring in two belts (Figure 13), that have been called the Ballou or New River belt and the Red Hill or Poison Branch belt. A third belt which is designated the titaniferous belt, contains a series of pits in titaniferous ores. The New River belt extends along the North Fork of New River, crossing it several times, and the Poison Branch is parallel to the New River belt, but 2 miles farther west. Neither belt consists of a continuous series of deposits, but each comprises a number of independent deposits on a series of nearly parallel veins lying close together. Some of the veins are short, being limited to the length of a single deposit, while others continue for comparatively long distances and comprises several deposits. The longest vein, perhaps, and that containing the greatest number of distinct deposits is that on the east side of New River about 1 « miles west of Crumpler. The deposits themselves are thin lenses that lie in the courses of the veins, which in turn are parallel to the structure of the shists in which they lie.
The ore has been stated to occur in thin lenses, but as a matter of fact, the commercial portions of the ore bodies are often in the form of veins or dikes of rich magnetite that cut masses of leaner ore. The lean ores comprises the lenses. Where these are enriched by the magnetite veins they have furnished the commercial products. Pratt states:
“the deposits are undoubtedly lenticular… and are pinching and widening in all dimensions. These lenses may continue for long distances along the strike and on the dip; then again, there may be a series of smaller lenses separated from each other by country rock or connected with each other by a thin seam of ore. Sometimes they may be so small as to be of no commercial value; while at other times they attain enormous size, both in length and depth. Usually these ore deposits are conformable to the enclosing country rock. Each ore locality has to be investigated as a separate unit, inasmuch as there is great variation in them….”
The ores of all the deposits are granular mixtures of pyroxene, hornblende and magnetite or of magnetite, hornblende, epidote, and quartz. Most of the pyrozene and magnetite grains are cracked or shattered and the quartz is largely granulated. The epidote, where it occurs, is an alteration product of plagioclase. These rather low grade ores occur as veins from a few inches to 17 to 20 feet wide traversing gneisses or gnessoid granites parallel to their schistosity. In many places these veins are cut by veinlets of nearly pure magnetite, thus enhancing their content or iron.
The old mines are difficult to study, since they have been long abandoned and originally they were never thoroughly developed. There is now little visible at their openings. Some information concerning them has been furnished by the geologists of the Tenth Census and by Mr. Nitze, but very little of it is of geological value. (Omitted pages 136-147 of the original)
Analyses of samples of ore from the slope and one of loose ore found at the mouth of the tunnel are quotes from Nitze’s report:
Partial analyses of ore from Francis property, Ashe County, N.C.
|Phosphorus ratio (P:Fe)||.213||.180||.186|
Openings on Turkey Knob
The Stewart land referred to by Nitze is on the west side of the summit of Turkey Knob, about half a mile west of the Francis land. When this place was visited two trenches were found, but evidently they are not the openings that were described by Nitze, as they show evidence of much later working. In neither trench was any ore seen in place, but on their dumps were fragments of lean ore, some of which consisted of a hornblende gneiss with scattered grains of magnetite and others of parallel layers of brown quartz, hornblende schist and a dark schist containing magnetite.
The brown layers contain subordinate white sugary quartz seams, and the magnetite layers much hornblende. The brown layers are composed mainly of interlocking quartz grains, with here and there embedded in the aggregate large and small pink garnets, an occasional flake of biotite and more frequent, but not common, wisps of uralite. The garnets are arranged in lines and the biotite and uralite are clongate in the same direction. The quartz, however, is in equidimensial grains and there is no evidence of a definite parallelism among them.
The darker layers differ from the lighter ones only in the greater amount of uralite they contain and in the presence in them of a little magnetite and epidote. The magnetite is in clongate grains and small masses and the epidote in small crystals and grains intermingled with the amphibole. The quartz grains are slightly elongate in a common direction, which is the same as that of the elongation of the magnetite and amphibole. In non of the grains are there any strain shadows, visible.
The specimen studied is not an ore. It is a schist that has been strongly silicified.
Nitze states in his description of the locality that the ore found at two openings, 100 feet apart in elevation is a hard, compact crystalline magnetite in a 5 foot vein having “a gauge of epidote, gneiss and quartz.”
He gives analyses of two samples:
Partial analyses of samples of ore from the top of Turkey Knob, Ashe County, N.C.
|Phosphorus ratio (P:Fe)||.025||.048|
In a third analysis of the same ore a trace of TiO [Titanium oxide] was found.
About half a mile S. 30 degrees W. Of the Francis property is the center of a considerable exploration on the lands of the Graybeal heirs. (Figure 15). The deposits here were worked a long while ago to furnish local forges with ore. Nitze describes two openings on the property– one a narrow open cut 50 feet long, “showing a bed of soft shot ore in decomposed hornblende,” with a one-foot thick seam of manganiferous earth in its “front part.” He does not state just where this cut was but it was probably on the southwest slope of the hill on the summit of which is the larger main opening. This main opening was a cut 50 feet long near the summit of the ridge. The 4-foot seam was a compact magnetite free from gangue, while the upper, 18-foot seem contained some hornblende. Analyses of sample from these seams are given as follows:
|Titanium dioxide (TiO2)||–||.06||–|
|Phosphorus ratio (P:Fe)||.019||.014||.009|
After Nitze’s visit much more work was done of the Graybeal and adjoining farms. Pratt describes this work and the new openings substantially as follows:
About one-half a mile northeast of the Waughbank (see page 185) propery begins what is know as the Graybeal properties. The first property encountered is the Calvin Graybeal. Only a very little development work has been done on this property, but float ore has been encountered, which would indicate the continuation of the ore formation across the property.
A short distance north from the top of the hill on the Calvin Graybeal property on lands owned by the Patton family and Calvin Graybeal, a cut exposed magnetic iron ore mixed somewhat with the country schist. This may be part of an ore deposit that is known in the section as the “North vein,” which extends approximately parallel with the regular ore formation, being approximately 200 to 300 yards north of the larger vein.
It is about one-fourth mile from the top of the Calvin Graybeal hill to the Joseph Graybeal property of an approximately northeast direction. The vein has a strike across the southeast. The ore deposit has been prospected and developed by means of open cuts, pits, and tunnels for a lateral distance of at least 800 feet and a vertical distance of over 100 feet. A drill hole was make by the Pulaski Iron Company at a point about 700 feet to the southeast of the first open cut, and 75 feet below. It is reported to have encountered the ore at a depth of about 200 feet. The dip of the vein would bring the ore body to this point. The width of the ore body as encountered varied from 4 to 15 feet.
The first cut examined was partially filled, in that the extent of the vein could not be determined. Good ore is exposed in the cut, thus showing the continuance of the ore body. This work was done by the Virginia Iron, Coal and Coke Company in 1907. Three hundred feet to the northeast, another cut exposed the vein, which had a width of at least 15 feet of nearly solid ore, there bing a little of the ore mized with finely divided gangue rock. An analysis of this ore showed 63.50 per cent, metallic iron. At the mouth of the cut, about 30 feet from the vein, another small seam of ore 12 to 15 inches was exposed. Most of this work was done about 1890 or 1892. Part of it was done in the early days of iron mining in the county, when the ore was obtained for the Catalan forges.
Still further to the northeast a long open cut or trench was made by Mr. Sturgill in 1903 across the ore deposit. At the time of my visit, however, it was nearly all filled up and the ore was only explosed at the east end of the cut.
Float ore has been found between all the cuts referred to.
On the opposite side of the hill several cuts and tunnels have been run which penetrated the ore body, showing that the ore was continuous through this hill. Most of the work was done by the Virginia Iron, Coal and Coke Company in 1907. The first cut is about 300 yards northeast of the Sturgill cut referred to above…. Near the mouth of the cut an iron manganese seam of ore was encountered 6 feet wide, the distance between the two veins being 30 feet.
Thirty feet below this cut a tunnel was run into the hill…. Judging from the material found on the dump, the ore encountered in the tunnel was very similar to that in the cut referred to above.
Two hundred and fifty feet northeast of this tunnel another open cut was made by Dr. Tom Jones in 1905, and work was continued by the Virginia Iron, Coal and Coke Company in 1907. This cut exposed a seam of magnetite about 4 feet wide, which it penetrated. In the upper end of the cut there was exposed a mixture of pyrite and hornblende. Thirty feet below and 20 feet northeast of this cut a tunnel was run by the Virginia Iron, Coal, and Coke Company, and later continued by Dr. Jones. This penetrated the ore body. There was exposed near the mouth of the tunnel a manganese iron seam of ore.
From this point it is 300 yards to the Joseph Graybeal line. Beyond this property is the Dr. Thomas Jones land which has been prospected…. by means of shallow cuts and pits.
Analyses of ore from 3 of the openings were made by Crowell and Murray. The results quoted by Pratt are given in the following table:
Partial analyses of ore from the Jos. Graybeal property, near Lansing, Ashe County, N.C.
|Element||First Cut||Second Cut||Large Cut,
Top of Hill
|Titanium dioxide (TiO2)||.00||–||–|
On the writer’s visit to the Graybeal property in 1919 a number of openings were seen in a northeast line, but it was difficult to identify any of them with those described by Nitze or Pratt. Some of the openings are comparatively recent. Mr. Cooke, who made some of the newer openings and enlarged some of the older ones, declares that he shipped from the them about 1,000 tons of ore. He followed a rich vein varying in width from 18 inches to 12 feet, that cut through a larger vein of lean ore composed of magetite, hornblende, and epidote. The rich ore runs irregularly through the vein-metter but on the whole, it follows the strike of the larger vein, which is about northeast. In some places small quartz and pegmatite veins also traverse the lean ore. At some of the other openings there were noticed also veinlets of pure magnetite cutting vein-matter irregularly but they never cross the borders fo the vein proper which usually trends in a straight line.
Analyses of carload lots of the Graybeal ore aggregating 911 tons showed limits of 44.00-61.08 percent for iron and 0.0088-0.0262 per cent for phosphorus. All the cars but two showed more than 50 per cent of iron and their average was 54.30 per cent.
The analysis of a carload of the ore mined by Mr. Cooke in June 1916, showed:
Partial Analyses of Graybeal ore, Lansing, Ashe County, N.C.
|Silica (SiO2)||12.16||Lime (CaO)||3.35|
|Iron (Fe)||6.180||Magnesia (MgO)||2.00|
|Manganese (Mn)||1.82||Titanium (Ti)||.012|
|Copper (Cu)||.00||Phosphorus (P)||.00094|
A few years ago a tunnel was started near the bottom of the south slope of the hill a few yards north of the road between Lansing and Piney Creek in order to reach the lower portions of the deposits that outcrop on the crest of the hill 180 feet higher, but work was stopped before the ore was reached and there is thus no evidence to indicate whether the deposits continue to so great a depth or not.
All the deposits in this area are certainly not on the same vein. Some of the veins may bend slightly and deposits not on the same straight line may indeed be the richer parts of a continuous vein. But the positions of the deposits with respect to each other are such that many of them cannot be explained on this supposition. It is much more probable that they are on different but parallel veins. Mr. Cooke, who has explored the country around Lansing pretty thoroughly insists that there are 5 distinct veins between the Ashe Mining Co.’s mine (see figure 15) and Dr. Jones’s house which is about half a mile northeast of Lansing station.
It would seem unwise to attempt to work any of the deposits on the Graybeal property without providing some means for concentrating the ore, since in most cases it would be necessary to remove a slice of material 15 or 20 feet wide to gain room for mining. This would mean that would could not be limited to the rich narrow veins that intersect the lower grade ore that comprises the greater parts of the larger veins. Some veins might be worked profitably for a short time, but only by following their richest parts until a depth is reached beyond which the cost of raising the crude ore would be prohibitive. This depth would not be great with veins only 4 feet or 5 feet wide. Moreover, all but the richest ore would be left and therefore wasted, since it would not of itself bear the cost of mining. On the assumptiopn of a minable width of 17 feet of material containing 75 per cent of magnetite, and a length of 800 feet, the avialable marketable ore above the mouth of the tunnel on the south side of the hill after concentration would amount to about 150,000 tons.
About half a mile southwest of the Graybeal openings is the Waughbank property which consists of an open cut and a tunnel on the hill on the north bank of Horse Creek near where it crosses the Virginia and Carolina Railroad, 1 « miles southeast of Lansing station. Reference will again be made to the deposit at this place in the discussion of the Ashe Mining Co.’s mine. (See p. 183)
Hampton Knob Openings
About three-quarters of a mile west of the Graybeal mine and about the same distance northwest of the Waughbank opening a vein crosses the north end of the crest of Hampton Knob where it has been opened by a shallow pit. Other pits and shallow trenches have been made on the northeast slope of the knob, but they have uncovered only small veins. These openings are sufficiently numerous to indicate the presence of ore veins, but are not so distributed as to indicate whether they are on the same vein or not. It is probable that no one of the veins is continuous with any of those opened on the Graybeal land. Nitze declares that the Hampton Knob ore lacks the manganiferous character of the Graybeal ore and most probably therefore is on an independent parallel vein. He gives 3 analyses of which one is reproduced below.
Partial analyses of ore from Hampton Knob, Lansing, Ashe County, N. C.
|Silica (SiO2)||9.66||Phosphorus (P)||.91|
|Iron (Fe)||61.58||Phosphorsu ratio (P:Fe)||.016|
Openings southwest of Hampton Knob
Southwest of Hampton Knob other deposits are known to be on the general strike of those on the knob, but they were not visited. Nitze states that a quarter of a mile northwest of Dresden which is at the junction of Stagg’s Creek and North Fork of New River, a shallow cut on the land of Dr. Wilcox uncovered a 12-foot vein of ore in a gaugue of hornblende and epidote. The strike of the country rock is N 60 degrees E and its dip 36 degrees to 40 degrees SE. An analysis of the ore is quoted below.
Along North Fork and its tributaries from the west the country rock of gneiss, epidote, and hornblende is described as being “fairly charged with crystalline magnetite.” There have been many small openings made in the area. Some of these are promising but no deposits of value have been found. An outcrop near North Fork, about 2 miles south of Solitude was sampled and analyzed with the result shown:
Partial Analyses of magnetic ore from veins southwest of Hampton Knob, Ashe County, N.C.
|Element||Near Dresden||Near Solitude|
|Phosphorus ratio (P:Fe)||.036||.009|
Openings southeast of Lansing
Veins are known to exist southeast of Lansing that are independent of all of those that have been described in its vicinity. On the King property, about half a mile southeast of the Ashe Mining Co.’s mine, and west of the railroad is an old tunnel on the top of the hill. On its dump are banded gneisses that look like mica schists impregnated with granitic material. In these are layers of magnetite, in some cases as much as three-quarters of an inch thick. In other places the magnetite crosses the gneiss layers and includes slivers of them. Other fragments are of hornblende schist containing lenses of feldspar as though impregnation with granite material had taken place.
A section of the schist reveals the presence of large cellular hornblende anhedrons and large grains of fledspar lying in an aggregate of small grains of feldspar and a few of quartz and epidote. In the midst of this aggregate are crystals and large irregular broken masses of magnetite. These are present also in the hornblende. Between the hornblende and feldspar is often a mixture of uralite and epidote with narrow streaks of pink garnet next to the hornblende. Tiny nests of calcite are among the decomposition products, whether they are mainly uralite or epidote. Scatters through the matrix are also little nests of calcite and quartz. Veinlets of garnet traverse the hornblende and veinlets of calcite cut through all parts of the slide.
Mr. Cooke who made the opening, furnished an analysis of a sample of the ore which showed: iron (Fe) 55.23 per cent and phosphorus (P) .0494 per cent.
Farther east and a little south of the King opening and about a third of a mile north of Bina, near the railroad but on the east side of Horse Creek, is a tunnel on Mr. Eller’s property. This cut 4 feet of ore at its mouth. The ore is in gneiss which near the main ore-body contains ore streaks rarely more than 1 foot thick. The ore is not visibly associated with epidote as it is elsewhere in this district. An analysis is not at hand.