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Id 27
Identification Type Mineral
Name Volcanic Glass
Distinguishing Features Isotropic
Vesicular
Description Transparent colorless to pale gray, green, or brown. Nonpleochroic. Isotropy is diagnostic feature, although devitrification may cause low-order birefringence at edges of grains. Moderate relief. May have bubble or pipe vesicles, stretching textures, cuspate to lunate bubble wall shards with sharp edges. May be disseminated throughout other sediment or occur in pure layers. Tephra may also contain crystalline grains from the same eruption or reworked material.
Tags bubbles
shards
sharp
ash
External Resources
Imposters Palagonite
Volcanic Glass can be altered to Palagonite
Images
Unique Identification: Volcanic Glass
Site name: Redfish Lake, ID
Light type: Plane-Polarized Light
Magnification: 400.0
Submitted by: Mark Shapley
Notes: Basaltic tephra, probably from the Snake River Plain. Fine mineral inclusions in vesicle.
Image Tags: mafic_tephra colored vesicular inclusions isotropic
Unique Identification: Volcanic Glass
Site name: Redfish Lake, ID
Light type: Cross-Polarized Light
Magnification: 400.0
Submitted by: Mark Shapley
Notes: Basaltic tephra, probably from the Snake River Plain. Fine mineral inclusions in vesicle.
Image Tags: mafic_tephra colored vesicular inclusions isotropic
Unique Identification: Volcanic Glass
Site name: Pettit Lake, ID
Light type: Plane-Polarized Light
Magnification: 400.0
Submitted by: Mark Shapley
Notes: Glacier Peak 'G'(?) tephra
Image Tags: none
Unique Identification: Volcanic Glass
Site name: Pettit Lake, ID
Light type: Cross-Polarized Light
Magnification: 400.0
Submitted by: Mark Shapley
Notes: Glacier Peak 'G'(?) tephra
Image Tags: isotropic conchoidal
Unique Identification: Volcanic Glass
Site name: Pettit Lake, ID
Light type: Plane-Polarized Light
Magnification: 400.0
Submitted by: Mark Shapley
Notes: Glacier Peak 'G'(?) tephra; vesicular pumice fragment.
Image Tags: none
Unique Identification: Volcanic Glass
Site name: Pettit Lake, ID
Light type: Cross-Polarized Light
Magnification: 400.0
Submitted by: Mark Shapley
Notes: Glacier Peak 'G'(?) tephra; vesicular pumice fragment.
Image Tags: vesicular pumice
Unique Identification: Volcanic Glass
Site name: Pettit Lake, ID
Light type: Plane-Polarized Light
Magnification: 400.0
Submitted by: Mark Shapley
Notes: Glacier Peak 'G'(?) tephra
Image Tags: none
Unique Identification: Volcanic Glass
Site name: Pettit Lake, ID
Light type: Cross-Polarized Light
Magnification: 400.0
Submitted by: Mark Shapley
Notes: Glacier Peak 'G'(?) tephra
Image Tags: conchoidal isotropic
Unique Identification: Volcanic Glass
Site name: Pettit Lake, ID
Light type: Plane-Polarized Light
Magnification: 400.0
Submitted by: Mark Shapley
Notes: Mt. St. Helens 'Y' series(?) tephra
Image Tags: none
Unique Identification: Volcanic Glass
Site name: Pettit Lake, ID
Light type: Cross-Polarized Light
Magnification: 400.0
Submitted by: Mark Shapley
Notes: Mt. St. Helens 'Y' series(?) tephra
Image Tags: vesicular isotropic
Unique Identification: Volcanic Glass
Site name: Pettit Lake, ID
Light type: Plane-Polarized Light
Magnification: 400.0
Submitted by: Mark Shapley
Notes: Glacier Peak 'G'(?) tephra
Image Tags: none
Unique Identification: Volcanic Glass
Site name: Pettit Lake, ID
Light type: Cross-Polarized Light
Magnification: 400.0
Submitted by: Mark Shapley
Notes: Glacier Peak 'G'(?) tephra
Image Tags: isotropic conchoidal
Unique Identification: Volcanic Glass
Site name: Pettit Lake, ID
Light type: Plane-Polarized Light
Magnification: 400.0
Submitted by: Mark Shapley
Notes: Mt. St. Helens 'Y' series(?) tephra
Image Tags: none
Unique Identification: Volcanic Glass
Site name: Pettit Lake, ID
Light type: Cross-Polarized Light
Magnification: 400.0
Submitted by: Mark Shapley
Notes: Mt. St. Helens 'Y' series(?) tephra
Image Tags: isotropic
Unique Identification: Volcanic Glass
Site name: Yellowstone
Light type: Plane-Polarized Light
Magnification: 630
Submitted by: Val Stanley
Notes: volcanic glass shard with bubble junctions still intact
Image Tags: vesicular volcanic
Unique Identification: Volcanic Glass
Site name: Lewis Lake
Light type: Plane-Polarized Light
Magnification: 400
Submitted by: Val Stanley
Notes: shard morphologies
Image Tags: pyroclastic
Unique Identification: Volcanic Glass
Site name: Yellowstone
Light type: Plane-Polarized Light
Magnification: 630
Submitted by: Val Stanley
Notes: Note aligned mineral inclusions
Image Tags: mineral-inclusions
Unique Identification: Volcanic Glass
Site name: Evans Lake
Light type: Plane-Polarized Light
Magnification: not specified
Submitted by: Andy Breckenridge
Notes: volcanic ash, tephra
Image Tags: none
Unique Identification: Volcanic Glass
Site name: Jones
Light type: Plane-Polarized Light
Magnification: 400.0
Submitted by: Mark Shapley
Notes: glassy vesicular stretched
Image Tags: none
Unique Identification: Volcanic Glass
Site name: Bay Horse Lake, ID
Light type: Plane-Polarized Light
Magnification: 400.0
Submitted by: Mark Shapley
Notes: Highly vesicular (pumaceous) volcanic glass from a basaltic tephra originating in the Snake River Plain, Idaho. Vesicles give colorless glass an opaque appearance in plane-polarized light.
Image Tags: volcanic-glass vesicular bubbles dark isotropic
Unique Identification: Volcanic Glass
Site name: Bay Horse Lake, ID
Light type: Cross-Polarized Light
Magnification: 400.0
Submitted by: Mark Shapley
Notes: Highly vesicular (pumaceous) volcanic glass from a basaltic tephra originating in the Snake River Plain, Idaho. Almost wholly isotropic in cross-polarized light.
Image Tags: volcanic-glass vesicular bubbles dark isotropic
Unique Identification: Volcanic Glass
Site name: Bay Horse Lake, ID
Light type: Plane-Polarized Light
Magnification: 400.0
Submitted by: Mark Shapley
Notes: Partially altered (palagonitic?) volcanic glass from a basaltic tephra originating in the Snake River Plain, Idaho. Altered regions show yellowish-brown discoloration of near-colorless fresh glass.
Image Tags: volcanic-glass low-birefringent zeolite alteration
Unique Identification: Volcanic Glass
Site name: Bay Horse Lake, ID
Light type: Cross-Polarized Light
Magnification: 400.0
Submitted by: Mark Shapley
Notes: Partially altered (palagonitic?) volcanic glass from a basaltic tephra originating in the Snake River Plain, Idaho. Altered regions show diffuse, low-order birefringence.
Image Tags: volcanic-glass low-birefringent zeolite alteration
Unique Identification: Volcanic Glass
Site name: Bay Horse Lake, ID
Light type: Plane-Polarized Light
Magnification: 400.0
Submitted by: Mark Shapley
Notes: Sharp vesicular shard of basaltic glass originating in the Snake River Plain, Idaho. Small altered show as birefringent patches.
Image Tags: volcanic-glass alteration vesicular isotropic zeolite
Unique Identification: Volcanic Glass
Site name: Bay Horse Lake, ID
Light type: Cross-Polarized Light
Magnification: 400.0
Submitted by: Mark Shapley
Notes: Sharp vesicular shard of basaltic glass originating in the Snake River Plain, Idaho. Small altered regions appear brown or yellowish.
Image Tags: volcanic-glass alteration vesicular isotropic zeolite
Unique Identification: Volcanic Glass
Site name: Bay Horse Lake, ID
Light type: Plane-Polarized Light
Magnification: 400.0
Submitted by: Mark Shapley
Notes: Sand-sized vesicular glass from a basaltic tephra originating in the Snake River Plain, Idaho. Grain at lower right is dark in plane-polarized light, while grain in upper left quadrant appears colorless.
Image Tags: volcanic-glass vesicular isotropic greenish-brown dark
Unique Identification: Volcanic Glass
Site name: Bay Horse Lake, ID
Light type: Cross-Polarized Light
Magnification: 400.0
Submitted by: Mark Shapley
Notes: Sand-sized vesicular glass from a basaltic tephra originating in the Snake River Plain, Idaho. Most of the glass is fully extinct in cross-polarized light.
Image Tags: volcanic-glass vesicular isotropic greenish-brown dark
Unique Identification: Volcanic Glass
Site name: Tyrrhenian Sea, Mediterranean
Light type: Plane-Polarized Light
Magnification: not specified
Submitted by: Guy Rothwell
Notes: Field of volcanic glass shards showing a wide range of shard morphology, including semi-regular fragments packed with subparallel pipe vesicles and vesicular glass fragments and bubble wall shards, volcanic-glass pyroclastic pipe-vesicles shards
Image Tags: none
Unique Identification: Volcanic Glass
Site name: Bay Horse Lake, ID
Light type: Plane-Polarized Light
Magnification: 400.0
Submitted by: Mark Shapley
Notes: Concoidally fractured, strongly colored volcanic glass from a basaltic tephra originating in the Snake River Plain, Idaho. Insect wing to the right provides textural aesthetic counterpoint.
Image Tags: conchoidal-fracture volcanic-glass dark isotropic
Unique Identification: Volcanic Glass
Site name: Bay Horse Lake, ID
Light type: Plane-Polarized Light
Magnification: 400.0
Submitted by: Mark Shapley
Notes: Partially altered volcanic glass from a basaltic tephra originating in the Snake River Plain, ID. Altered regions (palagonitized?) are yellowish and localized preferentially on vesicle walls.
Image Tags: volcanic-glass low-birefringent zeolite
Unique Identification: Volcanic Glass
Site name: Bay Horse Lake, ID
Light type: Cross-Polarized Light
Magnification: 400.0
Submitted by: Mark Shapley
Notes: Partially altered volcanic glass from a basaltic tephra originating in the Snake River Plain, ID. Altered regions (palagonitized?) are weakly birefringent.
Image Tags: volcanic-glass low-birefringent zeolite
Unique Identification: Volcanic Glass
Site name: Bay Horse Lake, ID
Light type: Plane-Polarized Light
Magnification: 400.0
Submitted by: Mark Shapley
Notes: Partially altered volcanic glass from a basaltic tephra originating in the Snake River Plain, ID. Altered regions (palagonitized?) are yellowish-brown.
Image Tags: volcanic-glass low-birefringent zeolite alteration
Unique Identification: Volcanic Glass
Site name: Bay Horse Lake, ID
Light type: Cross-Polarized Light
Magnification: 400.0
Submitted by: Mark Shapley
Notes: Partially altered volcanic glass from a basaltic tephra originating in the Snake River Plain, ID. Birefringent alteration is localized along a tubule in the glass fragment.
Image Tags: volcanic-glass low-birefringent zeolite alteration