Cordierite from
Timms Hill (Tim's Hill; Iolite Hill), Haddam, Middlesex County, Connecticut, USA
| Locality type: | Hill | |
| Classification | ||
|---|---|---|
| Species: | Cordierite | |
| Formula: | (Mg,Fe)2Al3(AlSi5O18) | |
| 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 | β6 photos of Cordierite associated with Chlorophyllite at this locality. | |
| Fahlunite | β5 photos of Cordierite associated with Fahlunite at this locality. | |
| Quartz | β2 photos of Cordierite associated with Quartz at this locality. | |
| Albite | β2 photos of Cordierite associated with Albite at this locality. | |
| Schorl | β1 photo of Cordierite associated with Schorl at this locality. | |
| 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 (6 photos) | |
| Data Identifiers | ||
| Mindat Occurrence Record ID: | 134155 | |
| Long-form Identifier: | 1:3:134155:3 | |
| GUID (UUID V4): | eb9462bc-990a-40d9-a990-185a9c9ca619 | |
| Nearest other occurrences of Cordierite | ||
| 1.4km (0.9 miles) | βChrysoberyl locality, Haddam, Middlesex County, Connecticut, USA | |
| 1.5km (1.0 miles) | βState Route 9 Interchange 13 - Beaver Meadow Road, Haddam, Middlesex County, Connecticut, USA | |
| 2.0km (1.3 miles) | βThulite locality, Haddam, Middlesex County, Connecticut, USA | |
| 4.6km (2.9 miles) | βUnnamed amphibole-tourmaline-magnetite locality, Haddam Neck, Haddam, Middlesex County, Connecticut, USA | |
| 12.2km (7.6 miles) | βGreat Hill cobalt mines, Cobalt, East Hampton (Chatham), Middlesex County, Connecticut, USA | |
| 14.7km (9.1 miles) | βStrickland Quarry, Strickland pegmatite, Collins Hill, Portland, Middlesex County, Connecticut, USA | |
| 14.8km (9.2 miles) | βSchoonmaker Mine, Strickland pegmatite, Collins Hill, Portland, Middlesex County, Connecticut, USA | |
| 17.9km (11.1 miles) | βCase Quarries, Portland, Middlesex County, Connecticut, USA | |
| 22.3km (13.8 miles) | βHungry Hill, Guilford, New Haven County, Connecticut, USA | |
| 37.6km (23.4 miles) | βEast Main Street construction site, Waterbury, New Haven County, Connecticut, USA | |
| References | ||
Timms Hill, Haddam, Middlesex County, Connecticut, USA