Cordierite from
Timms Hill (Tim's Hill; Iolite Hill), Haddam, Middlesex County, Connecticut, USA
| Locality type: | Hill | |
| Classification | ||
|---|---|---|
| Species: | Cordierite | |
| Formula: | Mg2Al4Si5O18 | |
| Formation: | Primary | |
| Comments: | Shows good cleavage and typically gemmy, though some of it is altered to dull gray-green "fahlunite". "The iolite has frequently been procured here in tabular plates, several inches across; and is remarkable for the facility with which it admits of cleavage into still thinner layers. This separation is undoubtedly promoted by the presence of exceedingly thin plates of what seems to be mica. The crystals are but seldom possessed of well defined lateral planes, in consequence of the implantation upon them of mica, albite, tourmaline, and more rarely of tabular spar. When perfect, however, they are either regular hexagonal prisms, or else this form, modified by the replacement of its lateral edges. Their color is a rich dark blue, with an occasional inclination to green; the depth of the color, as is usual in this species, is enhanced by the inspection of the plates in a direction perpendicularly to their cleavage." Shepard (1841) "Many beautiful specimens of a clear blue color have been found and cut into gems, showing dichroism by transmitted light. Specimens of this mineral seen in the different collections and museums of this country, you will invariably see labeled from Haddam. The alterations of this mineral are met with here in large quantities." (Davis, 1901). | |
| Habit: | pseudohexagonal prism, subhedral blocky to massive | |
| Colour: | violet, blue, pale green | |
| Quality for species: | Good crystals or rich for species - important (!) | |
| Abundance at site: | Common | |
| Confirmation | ||
| Validity: | Believed Valid | |
| Associated Minerals Based on Photo Data: | ||
| Chlorophyllite | 8 | |
| Fahlunite | 5 | |
| Albite | 3 | |
| Quartz | 3 | |
| Schorl | 1 | |
| Data | ||
| Mineral Data: | Click here to view Cordierite data | |
| Locality Data: | Click here to view Timms Hill (Tim's Hill; Iolite Hill), Haddam, Middlesex County, Connecticut, USA | |
| Photo Gallery | View Gallery (8 photos) | |
| Data Identifiers | ||
| Mindat Occurrence Record ID: | 134155 | |
| Long-form Identifier: | 1:3:134155:3 | |
| GUID (UUID V4): | 0 | |
| Nearest other occurrences of Cordierite | ||
| 1.4km (0.9 miles) | ⓘChrysoberyl locality, Haddam, Middlesex County, Connecticut, USA | |
| 1.5km (1.0 miles) | ⓘState Route 9 Interchange 13 - Beaver Meadow Road, Haddam, Middlesex County, Connecticut, USA | |
| 2.0km (1.3 miles) | ⓘThulite locality, Haddam, Middlesex County, Connecticut, USA | |
| 4.6km (2.9 miles) | ⓘAmphibole-tourmaline-magnetite locality, Haddam Neck, Haddam, Middlesex County, Connecticut, USA | |
| 12.2km (7.6 miles) | ⓘGreat Hill cobalt mines, Cobalt, East Hampton, Middlesex County, Connecticut, USA | |
| 14.7km (9.1 miles) | ⓘStrickland Quarry, Strickland pegmatite, Collins Hill, Portland, Middlesex County, Connecticut, USA | |
| 14.8km (9.2 miles) | ⓘSchoonmaker Mine, Strickland pegmatite, Collins Hill, Portland, Middlesex County, Connecticut, USA | |
| 17.9km (11.1 miles) | ⓘCase Quarry No. 1, Case Quarries, Portland, Middlesex County, Connecticut, USA | |
| 17.9km (11.1 miles) | ⓘCase Quarries, Portland, Middlesex County, Connecticut, USA | |
| 22.3km (13.8 miles) | ⓘHungry Hill mineral occurrence, Guilford, New Haven County, Connecticut, USA | |
| References | ||
Timms Hill, Haddam, Middlesex County, Connecticut, USA