The exploration for minerals in Rhode Island began long before the arrival of Europeans. The Native Americans made tools from quartz and used graphite and hematite for decoration. The first Europeans settlers searched the state for gold and silver but found none. Early colonials mined small deposits of iron and copper, which quickly proved uneconomic, but had extraordinary success quarrying granite for dimension stone and marble for lime. Coal and graphite were also worked with varying degrees of success until the 1960s.

The first article written solely on a Rhode Island mineral occurrence was on the discovery of what would become the state’s official mineral, bowenite (Bowen, 1822.) Bowenite was first thought to be a variety of nephrite jade but subsequent analysis has shown it to be a variety of antigorite, a member of the serpentine group (Smith and Brush, 1853). Finds of Rhode Island bowenite in the 1990s have revealed it to be formed by the metamorphic alteration of diopside, a common magnesium silicate.

Soon after Bowen’s article, Gerhard Troost (1823) and Charles Shepard (1824) published information about the first occurrence of the iron silicate ilvaite in the United States. The occurrence of this mineral would be debated much in later publications until the specimen was found again in the Academy of Natural Sciences of Philadelphia’s mineral collection 140 years later (Miller, 1972). Unfortunately this and another ilvaite specimen were lost again with the break-up of the Academy’s collection.

By 1824 there were enough minerals known from Rhode Island for Steuben Taylor, Thomas Webb, and Samuel Robinson to compile the first catalogue of Rhode Island minerals. Besides remarking on the discovery of ilvaite they brought attention to the amethyst crystals from Bristol. New discoveries of the minerals zoisite, molybdenite and magnetite were added to earlier reports of multi-colored fluorite from Cumberland. The authors investigated no less than thirteen small mines in Cumberland in which magnetite had been worked. Samuel Robinson later published “A Catalogue of American Minerals, with their Localities” in 1825 which was the first publication dedicated solely to minerals of the United States and Canada. All of the earlier knowledge of Rhode Island mineralogy was included with most of the state’s chapter dedicated to localities in Cumberland. No wonder the town was named after one of the most mineral rich areas of England.

The rest of the mineralogical publications on Rhode Island up to 1840 were dedicated again to individual localities and minerals. Nacrite, a chlorite group mineral, was noted from the Smithfield (now Lincoln) Lime quarries along with siderite, actinolite, and tremolite (Robinson, 1826). Yale University’s Benjamin Silliman made notes about the quality of Bristol amethyst (Anthony and Anthony, 1825; Robinson, 1825) and his student Charles Shepard found a rare member of the olivine group, fayalite, in Cumberland (Shepard, 1830).

In 1840, Chares T. Jackson, state geologist of Rhode Island, Maine, and New Hampshire, published his “Report on the Geological and Agricultural Survey of the State of Rhode Island” which was the first full geological survey of Rhode Island. Most of his Survey was about the bedrock and economic geology of Rhode Island (iron ores, lime, coal, granite, whet stones, and soil) but it did discuss some mineralogy in reference to a number of ore deposits especially in Cumberland. Shepard’s knebelite was discussed in length along with the actinolite and chalcopyrite found nearby. Also mentioned were minerals associated with the lime quarries such as antigorite and tremolite. Jackson also analyzed and coined the name “masonite” to a black platy mineral found by amateur mineralogist Owen Mason of Providence. The mineral later turned out to be a large, well crystallized variety of the silicate chloritoid.

Soon after, in 1841, Edward Hitchcock of Amherst College came out with his “Final Report on the Geology of Massachusetts.” Hitchcock included a portion on the mineralogy of Rhode Island and noted the mineralogy of the Smithfield lime quarries, Mount Hope in Bristol, and added several new minerals from Newport and Middletown. He also listed all the Rhode Island minerals located in the State of Massachusetts’ geological collection.

Most of the work of the late nineteenth century again relates to the bedrock and economic geology of Rhode Island, mostly about the Portsmouth coal mines. Cumberlandite, eventually designated the state rock, was proposed as the name of the titaniferous magnetite melatroctolite in the northern part of the state (Wadsworth, 1884) and a few new mineral localities were added (Random Notes, 1884). In 1887, the Providence Franklin Society published “Geology of Rhode Island” which assembled a small list of minerals mentioned in Jackson’s 1840 report. This was the most comprehensive report of minerals found in Rhode Island before C. Abbott Davis published the “Check List of Rhode Island Minerals” in 1905.

Davis’ list built on the Franklin Society’s list and added minerals from the collection of the Museum of Natural History, Roger Williams Park, Providence, as well as those of private collectors. He also revised the Franklin Society’s outdated nomenclature and arranged the list systematically. This list was the foundation of L.W. Fisher, C. G. Doll and E. K. Gedney’s “Notes on the Mineral Localities of Rhode Island” published in two parts through 1926 and 1927 in American Mineralogist. This was the first list of minerals compiled by professional geologists with specimens and localities verified by the authors. It remained the official state list until 1971.

In 1971, URI geologist Clarence E. Miller published the first edition of his “Minerals of Rhode Island.” In this volume he assembled the previous lists of minerals, added rock-forming minerals from geological studies, and included numerous minerals discovered since 1927. He also searched for specimens at the Academy of Sciences in Philadelphia, Harvard, Yale, and Boston College. Miller also added a great variety of minerals from the collection of Gil George who collected minerals during the construction of the Interstate Highway system in Rhode Island. These specimens are still preserved at Harvard and many were x-ray verified. He also noted whether specimens are from localities, lost, still open, and whether the report is questionable. The second edition in 1972 contains comments and edits from the author and O. Don Hermes, then associate professor of geology at the University of Rhode Island. This is still the most comprehensive list of Rhode Island minerals.

The bedrock and coal deposits of Rhode Island have been exhaustively studied but studies on the mineralogy of Rhode Island have been completely inadequate. All but one reference is at least seventy-five years old and there have been many new finds and advances in technology since the publication of Miller’s Minerals of Rhode Island. For example, chamosite, an iron-rich member of the chlorite group, was recently discovered in Exeter (Rakovan, personal communication 2008). Only two localities have been properly investigated in recent years. In the late1980s a spectacular find of amethyst was found in Hopkinton (Rakovan, et al 1995) and a very detailed description was published on an Alpine-type vein mineral assemblage in Cumberland (Cahoon and Young, 1986). The Cumberland site succumbed to development and the Hopkinton site is nearing its end. Fortunately these sites were documented but many others are only known through historical record or a few museum specimens. A more detailed mineralogical survey of the state is warranted before more locations completely disappear and we loose part of the state’s natural heritage forever.


Works Cited

1. Anonymous (1884a) Hornblende penetrating quartz, Calumet Hill, Cumberland. Random Notes on Natural History, 1:1, 3

2. Anonymous (1884b) Rhode Island iron. Random Notes on Natural History, 2:5, 3

3. Anonymous (1884c) Quartz crystals of Cumberland and Smithfield. Random Notes on Natural History, 2:6, 6

4. Anthony, J.G. and Anthony, J.B. (1825) Miscellaneous localities of minerals on Rhode Island, American Journal of Science, 9, 46-47

5. Bowen, G.T. (1822) Analysis of nephrite, from Smithfield, R.I. American Journal of Science, 5, 346-348

6. Cahoon, J. and Young, P. (1986) Minerals of Poker Hill, Cumberland, Providence County, Rhode Island. Rocks and Minerals, 61, 281-284

7. Davis, C.A. (1905) Check list of the minerals of Rhode Island, Roger Williams Park Museum Bulletin, 8

8. Fisher, L.W. and Doll, C.G. (1927) Notes on the mineral localities of Rhode Island. American Mineralogist, 12, 427-436

9. Fisher, L.W. and Gedney, E. K. (1926) Notes on the mineral localities of Rhode Island. American Mineralogist, 11, 334-340

10. Jackson, C.T. (1840) Report on the geological and agricultural survey of the State of Rhode Island. Providence

11. Miller, C.E. (1971) Minerals of Rhode Island. O.D. Hermes, ed. Department of Geology, University of Rhode Island, Kingston, Rhode Island

12. Miller, C.E. (1972) Minerals of Rhode Island. O.D. Hermes, ed. Department of Geology, University of Rhode Island, Kingston, Rhode Island

13. Providence Franklin Society (1887) Report on the Geology of Rhode Island. Providence

14. Rakovan, J., Mitcheltree, D.B., Benton, L., and Avella, S. (1995) Amethyst on milky quartz from Hopkinton, Rhode Island. Mineralogical Record, 26, 83-89

15. Robinson, S. (1825a) A catalogue of American minerals with their localities. Boston

16. Robinson, S. (1825b) Miscellaneous localities of minerals on Rhode Island, American Journal of Science, 9, 49-53

17. Robinson, S. (1826) Miscellaneous localities of minerals (Rhode Island). American Journal of Science, 10, 225-227

18. Shephard, C.U. (1824) Miscellaneous localities of minerals (yenite of Cumberland, R.I.). American Journal of Science, 7, 251

19. Shephard, C.U. (1830) Ferro-silicate of manganese (Cumberland). American Journal of Science, 17, 142-144

20. Troost, G. (1823) Notice of the yenite of Rhode Island and several other American minerals. Academy of Natural Sciences, Philadelphia, Journal. 3, 223-224

21. Wadsworth M.E. (1884) Lithological Studies. Memoirs of the Museum of Comparative Zoology, Harvard College, Cambridge, Mass., 129-132

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