Ron Schott's Geology Home Companion Blog

Concluding the geomeme of sand for this week… if you’re up to the challenge, comment on what you think the composition of the sand is and where it’s from. We’ll find out who knows their sand…

“Salt & Pepper” Sand (Macro)

“Salt & Pepper” Sand (15mm microscopic)

“Salt & Pepper” Sand (microscopic closeup)

*Not actual salt and pepper.

[Update: Okay, I cheated a bit here. This is not in fact a natural sediment - rather it is the sand size separate from a mechanical crush of fresh Half Dome Granodiorite, originating from near Olmstead Point in Yosemite National Park. If I had collected actual sand from this area I doubt the biotite grains would be quite so fresh and unweathered. By the way, did you spot that little wedge of sphene (titanite) in the most magnified view?]

Continuing the geomeme of sand for this week… if you’re up to the challenge, comment on what you think the composition of the sand is and where it’s from. We’ll find out who knows their sand…

White Sand (Macro)

White Sand (15mm microscopic)

White Sand (microscopic closeup)

[Update: Another easy one. This is, of course, gypsum sand from White Sands National Monument, near Alamagordo, New Mexico. Not an easy one to photograph well, as it turns out.]

Continuing the geomeme of sand for this week*… if you’re up to the challenge, comment on what you think the composition of the sand is and where it’s from. We’ll find out who knows their sand…

Multicolored Sand (Macro)

Multicolored Sand (15mm microscopic)

Multicolored Sand (microscopic closeup)

*Although this post has Wednesday’s date on it, I’m actually posting it and the other “sand series” posts late Thursday evening.

[Update: No doubt this one seems to have turned out to be the hardest nut to crack in the bunch. As it turns out, this is dune sand from Great Sand Dunes National Park in Colorado, collected just east of Medano Creek - the famous pulsating river. Despite the compositional immaturity of the grains, they are dominantly well rounded, and texturally well sorted.]

Continuing the geomeme of sand for this week*… if you’re up to the challenge, comment on what you think the composition of the sand is and where it’s from. We’ll find out who knows their sand…

Green Sand (Macro)

Green Sand (15mm microscopic)

Green Sand (microscopic closeup)

*Although this post has Tuesday’s date on it, I’m actually posting it and the other “sand series” posts late Thursday evening.

[Update: There really wasn't much suspense about this one at all. Any geologist who's visited the Big Island of Hawaii or knows another who did has probably heard of the Green Sand Beach at Pu'u Mahana, Hawaii. The green color is, of course, imparted by the high abundance of olivine grains in the pocket beach below this eroding littoral cone near the southern tip of the Big Island.]

It seems to be “Sand Week” in the geoblogosphere*. Ian Stimpson has been featuring deskcrops of local sandstones, and Brian Romans has reviewed Michael Welland‘s new book Sand: The Neverending Story (which just went into my Amazon shopping cart) and conducted a Q&A with Michael over at Clastic Detritus (how apropos). Callan Bentley gets to host the roving virtual book tour next week, followed by David Williams and Andrew Alden. (Kansans don’t read books, I guess, or maybe it’s just that sand is still a bit of a sore subject here. Anyhow, I know when I’ve been told to pound sand.)

So for this week’s deskcrop series, let’s see how much the experts know about their sand. Four distinctive sands on Monday thru Thursday, and then an evil stumper on Friday. If you’re up to the challenge, comment on what you think the composition of the sand is and where it’s from. We’ll find out who knows their sand…

Black Sand (Macro)

Black Sand (15mm microscopic)

Black Sand (microscopic closeup)

*Although this post has Monday’s date on it, I’m actually posting it and the following four “sand series” posts late Thursday evening.

[Update: As many of you were able to surmise this is indeed black sand from a Hawaiian beach. The sand is dominated by coarse, angular, well-sorted sand composed primarily of basaltic glass, with minor olivine. The locality of this sample is the Punalu'u Black Sand Beach, on the south shore of the Big Island of Hawaii.]