Sillimanite type locality, Chester, Middlesex County, Connecticut, USAi
| Regional Level Types | |
|---|---|
| Sillimanite type locality | - not defined - |
| Chester | Town |
| Middlesex County | County |
| Connecticut | State |
| USA | Country |
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Latitude & Longitude (WGS84):
41° 24' 9'' North , 72° 27' 2'' West
Latitude & Longitude (decimal):
Köppen climate type:
Nearest Settlements:
| Place | Population | Distance |
|---|---|---|
| Chester Center | 1,558 (2017) | 0.2km |
| Deep River Center | 2,484 (2017) | 2.5km |
| East Haddam | 9,042 (2017) | 5.7km |
| Essex Village | 2,495 (2017) | 7.2km |
| Moodus | 1,413 (2017) | 11.2km |
Nearest Clubs:
Local clubs are the best way to get access to collecting localities
Local clubs are the best way to get access to collecting localities
| Club | Location | Distance |
|---|---|---|
| Lapidary and Mineral Society of Central Connecticut | Meriden, Connecticut | 33km |
| New Haven Mineral Club | New Haven, Connecticut | 41km |
Bowen's (1823 & 1824) original description does not describe the locality, it just includes a short note saying "This mineral occurs in a vein of quartz, penetrating gneiss in the town of Saybrook, Connecticut, where, I am informed, it is found in considerable quantities." At that time, the town of Saybrook included the parish of Chester, which became a separate town in 1836, as well as the later towns of Westbrook (1840), Essex (1852, known as Pettipaug, Pettypaug, or Potopaug until 1854), and Old Saybrook (1854). The remainder, surrounding the original core town of Saybrook, changed its name to Deep River in 1947.
According to Silliman (1824), the type locality is "in the parish of Chester, on the left hand of the path [while traveling north], in a flat rock, which is chiefly mica-slate, I believe, lying a few rods south of the Post Office, is the above mineral, crystallized in veins of quartz. The Post Office is kept in a room of Denison's Tavern, near a small stream flowing into the Connecticut." This information was communicated by Dr. T. D. Porter, who according to Bowen (1824) found the rock in 1817. Denison's Tavern and the Post Office were located immediately south of Pattaconk Brook and just east of Main Street. A rod being 5.03 meters, the description places it indeed on the west (left) side of "the path" (then the old Middlesex County turnpike - now Main Street).
The area now (2012) is completely built out and graded and no outcrops are visible at the site and in the general area. There are however numerous stone retaining walls around graded areas and angular flat blocks and rip-rap along the very nearby Pattaconk Brook. Many of these appear to be at least partially derived from the local gray Tatnic Hill Formation gneiss, which underlies this area, others are clearly glacial erratics. Porter's description seems to indicate the source of the sillimanite was such a loose slab and not an outcrop. Similar brownish crystals in quartz have been found in veins in the Tatnic Hill Formation at the Falls of the Yantic in Norwich and near Willimantic.
Select Mineral List Type
Standard Detailed Gallery Strunz Chemical ElementsDetailed Mineral List:
| ⓘ Quartz Formula: SiO2 Habit: massive Description: massive vein traversing gneiss and hosting the sillimanite. References: |
| ✪ Sillimanite Formula: Al2(SiO4)O Habit: prismatic crystals with rhombic cross-sections Colour: clove-brown to gray Description: Prismatic crystals up to several inches long with rounded edges, some terminated. Probably found in a slab of loose gneiss. References: |
Gallery:
List of minerals arranged by Strunz 10th Edition classification
| Group 4 - Oxides and Hydroxides | |||
|---|---|---|---|
| ⓘ | Quartz | 4.DA.05 | SiO2 |
| Group 9 - Silicates | |||
| ⓘ | Sillimanite | 9.AF.05 | Al2(SiO4)O |
List of minerals for each chemical element
| O | Oxygen | |
|---|---|---|
| O | ⓘ Quartz | SiO2 |
| O | ⓘ Sillimanite | Al2(SiO4)O |
| Al | Aluminium | |
| Al | ⓘ Sillimanite | Al2(SiO4)O |
| Si | Silicon | |
| Si | ⓘ Quartz | SiO2 |
| Si | ⓘ Sillimanite | Al2(SiO4)O |
Other Regions, Features and Areas containing this locality
North AmericaContinent
North America PlateTectonic Plate
- Ganderia DomainDomain
- GranderiaPassive Margin
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References
books.google.be (n.d.) https://books.google.be/books/about/A_Catalogue_of_American_Minerals_with_Th.html?id=MDM4AAAAMAAJ&redir_esc=y
Robinson, Samuel (1825) A Catalogue of American Minerals, With Their Localities - Including All Which Are Known to Exist in the United States and British Provinces, And Having the Towns, Counties, and Districts in Each State and Province Arranged Alphabetically. With an Appendix, Containing Additional Localities and a Tabular View. Cummings, Hilliard, & Co.
Sillimanite type locality, Chester, Middlesex County, Connecticut, USA