Conrad Hill Mine (Dodge Hill Mine), Cid Mining District, Davidson County, North Carolina, USAi

Regional Level Types
Conrad Hill Mine (Dodge Hill Mine)	Mine
Cid Mining District	Mining District
Davidson County	County
North Carolina	State
USA	Country

Description: There is no ankerite at Conrad Hill. The carbonate is overwhelmingly siderite, and no calcium is present in the geochemistry. A myth of calling pseudomorphs of goethite after calcite rhombs "ankerite" became widespread at the Hiddenite localities in Alexander County, and this myth likely spread here since similar pseudomorphs after siderite occur here.

Description: Brochantite does not occur at Conrad Hill. I (Steve Adams) have not observed brochantite at this mine after half a century collecting there. I have regularly observed acicular malachite. The mine is very rich in carbonate but appears completely lacking in sulfates. Cited references do not mention brochantite.

Description: Chalcopyrite was the principle ore mineral at the Conrad Hill Mine. It was auriferous. The mine produced significant gold for a few decades in the early 1900's with accessory production of copper. Most of both came from the chalcopyrite, although grains of native gold dust contributed. The chalcopyrite is in spots and splotches in the quartz/siderite matrix rock of the ore body. Some of it is iridescent. Crystals, if they even exist, are exceedingly rare.

Description: The chlorite is in small flakes and crude crystals on milky quartz and sometimes impregnating the quartz. Decent small specimens with crystallized quartz are found occasionally.

Description: The mine often has red ocherous hematite, but dense maroon masses associated with chalcopyrite and malachite long inspired my suspicion that they were at least in part cuprite. The presence of the mineral finally became confirmed when I observed a specimen in the collection of Guilford College from a field trip they took there in the 1960's. There were small patches of poor acicular "chalcotrichite" variety cuprite on a piece of cellular goethite. The mineral should be considered rare and of poor quality. I myself collected a micro later of very tiny red crystals on quartz - not impressive.

Description: Was recorded as Limonite. The identity of goethite as the species is visually quite obvious. The mineral occurs in two major modes. The main interest in goethite here is the black mammillary masses. Very nice cabinet display pieces were relatively common half a century ago (1960's) but are hard to come by now. The other mode is brown cellular cavity-ridden pseudomorphs after siderite retaining some of the rhombic orientation in the walls of cavities. The interest here is finding nice malachite crystals in the vugs. Furthermore, nice rhombic pseudomorphs of goethite after siderite crystals are somewhat common. A lot of the quartz at the mine has drusy crystal surfaces richly impregnated by goethite, making attractive sparkly brown pieces.

Description: Hematite takes two modes at Conrad Hill: red ochre and black coarse platy. The platy is best described as "platy hematite" and does not resemble the variety "specularite". Tiny crystals are very rare and unimpressive, but they have been found. I (Steve Adams) found a few pieces with such crystals over many years of collecting there.

Description: Hematite takes two modes at Conrad Hill: red ochre and black coarse platy. The platy is not aptly descriptive as "specularite". The material does not resemble the sparkly compact variety specularite and should be called platy hematite.

Description: Malachite is common as small patches and stains, often with chalcopyrite. But within the void spaces of the cellular goethite, nice acicular crystals and silky or velvety sprays can be found with diligence. In the 1970's I (Steve Adams) broke open a piece of such goethite and was astonished to see a spray of several needles of malachite fine as a hair rising from a point a full inch tall! But holding it up in admiration, a strong wind gust came along and broke the crystals away!

Description: The listing of muscovite as a mineral at Conrad Hill can be misleading. What is present is a very fine grained sericite "schist" according to the literature, but certainly a phyllite. There are no visible mica flakes under a 15x hand lens. The rock resembles a creamy pale beige or greenish beige serpentine. It creates patches along with milky quartz and coarse cleavages of red-brown siderite. This combination makes attractive "yard rocks". Note that this rock is confined to the ore body and is absent in the country rock.

Description: See comments under muscovite. This is a very fine-grained phyllite with "sericite" as the primary constituent. No mica flakes can be seen under a hand lens.

Description: Most of the gold produced at the Conrad Hill Mine came from auriferous chalcopyrite. However, disseminated small grains of native gold contributed. Very rarely, pinhead size grains are found embedded in cellular goethite rock. Laurie Adams collected such a piece now in the Kenny Gay collection.

Description: One tends to think that pyrite would have to be at this mine. But in half a century of collecting I (Steve Adams) have seen none that I could be sure is pyrite and not chalcopyrite. See notes on chalcopyrite, the major ore mineral of the mine, which seems to be the only sulfide present.

Description: See notes under pyrite. If pyrite actually is present, it would likely be auriferous. The chalcopyrite is definitely auriferous, which in fact made the mine profitable.

Description: Milky quartz is abundant as a gangue mineral in the dump material, typically making nice contrast to siderite. Vugs and seams often have small crystals, rarely very clear. Drusy quartz surfaces are often impregnated with goethite making sparkling brown specimens. Much more rarely the quartz is chloritic.

Description: Very coarse cleavage masses of siderite comprise up to 40% of the gangue in the dump material. Single cleavage rhombs of ten centimeters across have been extracted. Intergrown red-brown coarse cleavage masses are plentiful and often attractive, especially with contrasting milky quartz. Often the quartz has seams and vugs of small crystals, and very sharp siderite crystals frequently occur with them. Habits are usually rhombs but also blades. Cavities directly in the siderite masses can show dull rhombs, often crude, up to three centimeters across. Finally, cellular brown goethite pseudomorphs after siderite rhombic crystals are fairly common. Single masses of siderite can weigh over a hundred pounds.