Wife Says Rock, I Think Not.

[grommit]

I think I have small mammal parts, and maybe a tooth.

My wife says the tooth is interesting rock with striations.

Found in austin chalk.

Also found that they will break if you hit with hammer. Not brightest moment.

These ones survived. Fell cleanly out of calk and left impression in fracture.

Do I have rocks or something better?

The "tooth" has parallel striations, and on one end, they are perpendicular to the lengthwise ones.

Other end is flat.

[marnixR]

what do the ends look like ?

[LanceH]

May be quartz.

[Uncle Siphuncle]

You won't find terrestrial mammal material in the Austin Chalk, a marine limestone.

[Xiphactinus]

you have an inoceramus bivalve and I believe a piece of gypsum....

[grommit]

Boy, responses on both sides. When I get home, I'll clean the quartz/bivalve more, and repost pictures at different angles.

[MOROPUS]

The first one looks like an oyster member (Gryphaea?),and the other,a broken piece of another marine animal (Aragonite?)

[LanceH]

First one is an oyster shell. Second one is a piece of quartz or similar mineral. Striated sheets of quartz (or similar) are common in limestone fractures and often they can look petrified wood or even long horse teeth.

I've also seen vertical quartz ridges several inches high and a couple inches thick criss-crossing a large flat exposure of soft Eagleford shale.

[Guest solius symbiosus]

I agree with X. The second one looks like gysum. What is it's hardness?

[grommit]

I agree with X. The second one looks like gysum. What is it's hardness?

How do I test hardness? The chalk came off with fingernail, this didn't break. Hitting another with a hammer accidentally broke it.

There's got to be a smarter way

I bought the texas field guide to fossils, but won't have time to read until this weekend. If there is an obvious explanation there, I'll find it.

I think lance is right. My first thought was baby horse tooth, which he says is quartz.

[Xiphactinus]

I'm positive that is gypsum....we find lots and lots just like that in the Kansas Chalk. He's a link I found with a quick Google search of the same type of crystal without the weathering.

http://www.collectorscorner.com.au/gemston...0Photos/237.jpg

[Guest solius symbiosus]

How do I test hardness? The chalk came off with fingernail, this didn't break. Hitting another with a hammer accidentally broke it.

There's got to be a smarter way

I bought the texas field guide to fossils, but won't have time to read until this weekend. If there is an obvious explanation there, I'll find it.

I think lance is right. My first thought was baby horse tooth, which he says is quartz.

Mohs Scale of Hardness

[LanceH]

I'm sure it's not gypsum, never seen any in the Austin chalk.

...now in the Eagleford just below the Austin you can find large crystals of clear gypsum.

oh, and I'm using "quartz" in a broad sense meaning a hard crystaline rock, not even sure if that's the correct mineral.

[Bill]

Looks like either fibrous Calcite, or a section of a broken, thick, Inoceramid shell. Many broken pieces of Inoceramus shells are found in the Chalk of Kent and Sussex. Much fibrous Calcite can be found in Dorset, England, among other places. It is found in layers called "Shales with Beef", (google).

[hybodus]

I agree with Lance... I have never seen or heard of gypsum in the Austin chalk.

N

[JohnJ]

I think Bill is right. I commonly find calcite in the rivers cutting the Austin Chalk. Using a weak acid solution will let you know...the calcite will dissolve and the gypsum will not react (and neither would quartz). The gypsum is soft and it can be scratched easily. Calcite is harder. I've rarely seen quartz occur in the chalk...mostly large veins of calcite. Sometimes the calcite forms spikey crystals that can look similar to quartz.