| Id | 47 |
| Identification Type | Mineral |
| Name | Quartz |
| Distinguishing Features | Low-birefringence
Equant |
| Description | Transparent colorless; equant grains; cleavage absent. Grains larger than ~30um show higher order birefringence colors (dark orange, pink), while smaller grains appear white or gray in cross-polarized light. May appear pitted, or show opaque or reddish coatings visible in plane polarized or reflected light. May be well-rounded where aeolian or fluvial transport contributes. Common mineral in detrital sediments and rock fragments. |
| Tags | silicate Transparent Colorless Low-relief |
| External Resources | Quartz on MinDat |
| Imposters |
Feldspar
Quartz and feldspar have similar low-order birefringence colors (white to gray) and regularly co-occur. They can be distinguished from each other by cleavage: feldspar has good cleavage, and quartz has no cleavage. That is, if the grain has a straight edge, it is more likely a feldspar, although exceptions occur. Polysynthetic twinning does not occur in quartz, and is a clear indicator of a feldspar when present. However many feldspars do not show such twinning. |
| Images |
|
Unique Identification: Quartz Site name: Reid Lake Light type: Plane-Polarized Light Magnification: not specified Submitted by: Andy Breckenridge Notes: angular quartz, undulose extinction, detrital, glaciolacustrine Image Tags: none |
|
Unique Identification: Quartz Site name: Reid Lake Light type: Cross-Polarized Light Magnification: not specified Submitted by: Andy Breckenridge Notes: Angular quartz, undulose extinction, detrital, glaciolacustrine Image Tags: none |
|
Unique Identification: Quartz Site name: not specified Light type: Plane-Polarized Light Magnification: 400x Submitted by: Amy Myrbo Notes: rounded coarse-grained Image Tags: none |
|
Unique Identification: Quartz Site name: not specified Light type: Cross-Polarized Light Magnification: 400x Submitted by: Amy Myrbo Notes: Well-rounded; sand-sized grain gives higher-order birefringence colors that expected for typical quartz silt. Image Tags: none |
|
Unique Identification: Quartz Site name: not specified Light type: Plane-Polarized Light Magnification: 400x Submitted by: Amy Myrbo Notes: well-rounded; stain Image Tags: none |
|
Unique Identification: Quartz Site name: not specified Light type: Cross-Polarized Light Magnification: 400x Submitted by: Amy Myrbo Notes: well-rounded; stain Image Tags: none |
|
Unique Identification: Quartz Site name: South Fraserdale, ON Light type: Plane-Polarized Light Magnification: not specified Submitted by: Andy Breckenridge Notes: angular quartz, detrital, glaciolacustrine Image Tags: none |
|
Unique Identification: Quartz Site name: South Fraserdale, ON Light type: Cross-Polarized Light Magnification: not specified Submitted by: Andy Breckenridge Notes: angular quartz, detrital, glaciolacustrine Image Tags: none |
|
Unique Identification: Quartz Site name: Arthurs Lake Light type: Plane-Polarized Light Magnification: 400 Submitted by: Val Stanley Notes: Note inclusions in quartz, likely rutilated Image Tags: rutilated |
|
Unique Identification: Quartz Site name: St. Louis River Light type: Plane-Polarized Light Magnification: 400 Submitted by: Val Stanley Notes: Note inclusion trails within quartz grain Image Tags: none |
|
Unique Identification: Quartz Site name: not specified Light type: Plane-Polarized Light Magnification: not specified Submitted by: not specified Notes: Rutilated Image Tags: none |
|
Unique Identification: Quartz Site name: not specified Light type: Cross-Polarized Light Magnification: not specified Submitted by: Guy Rothwell Notes: Field of poorly sorted angular quartz grains, anhedral Image Tags: none |
116 Church Street NE, Minneapolis, MN 55455
P: 612-626-7889