Monday, August 30, 2010

1. The Evils that beset mineral collections: Time

How many ways can time damage a mineral collection?
The primary problem is in the retention of information, but minerals themselves can also be damaged.

How can information be lost?
  • If you haven't written something down, it can be forgotten. That includes the location of samples and information. Take the time to label your specimens, even if with temporary labels, as you acquire them.
  • Sometimes notes (especially receipts) are not prepared using archival materials. Paper crumbles, ink fades, tape becomes unsticky. Try to avoid using non-archival materials; make copies of unstable notes.
  • Computer programs become obsolete over time; computer media may not be stable (e.g., many CDs are only rated for 10 years), or their related hardware may become obsolete. (For instance, my Ph.D. thesis is on large-format magnetic tape, and prior to that I used punch cards to index collection information: these are now dead media.) If your information is archived on hard media, update the media regularly, and check that the information has not become corrupted in the meantime; if it is in "the cloud," still make your own backups.
  • When the time comes to pass your collection along to another place, will you be there to handle the transfer? Or will your heirs know where the specimens are, which have special care issues, which label belongs to each specimen, and who gets what? Collections deserve special attention in the estate planning process. (And does the recipient know the collection is coming? Give your heirs a chance to prepare for the collection's arrival.)
What can happen to minerals?
  • Over time, minerals can react with their environment. Sharp water soluble crystals can become rounded due to humidity changes over time; some pyrite and marcasite crumble due to bacterial contamination; acid paper reacts with sulfide minerals.
  • Metastable minerals can revert or decompose: for instance, hydrous (or "hydratable") minerals gain or lose water.
Some of these changes can be mitigated with a stable environment and isolation of some specimens; but some is inevitable.

Monday, August 16, 2010

The evils that beset mineral collections: Intro

This next series is on the evils to which mineral collections are heir: the things that make a collection less valuable, or less educational, than it might have been:
1. Time
2. Space
3. Temperature and temperature changes
4. Humidity and humidity changes
5. Vibration and flexure
6. Dust
7. The Sun
8. Natural disasters
9. Moving
10. Insects and other pests
11. Children and other people
12. Loans, trades, and other collectors
13. Sulfur, pyrite, and other minerals
14. Newspaper, tape, glue, and other nonarchival materials
15. Inclination, boredom, lack of discipline, and new worlds to conquer
16. Poverty, death and the disposition of goods and records

Some of these are necessary evils in having both a mineral collection and a life, but let's watch out for them.

Comments are welcome for any evils or other topics you'd like me to mention.

Tuesday, August 10, 2010

Paris: City of Plaster

Paris is the most civilized city in the world. This French city is built on the human scale: narrow radiating streets guarantee shadows or sun (your choice) to walk in, cafes occupy most corners, and free public self-cleaning toilets are proliferating. Trees are omnipresent, a river runs through the center of town, the yellow-ochre-tinted sandstone buildings bounce back the light. Public transportation is easy and convenient. The people are professional and friendly when approached with a "Bonjour, Madame" or "Bonjour, Monsieur."

Paris also prides itself as a source of civilization, a city of paintings and statues and elegant design. Its museums are also filled with exotic dinosaurs, extinct mammals, engineering marvels, and more. My argument here is that Paris owes much of its artistic and scientific ability to civilize the world to the deposits of gypsum on which it sits.

Gypsum is calcium sulfate dihydrate; when most of the water is driven off, powdered calcium sulfate hemihydrate is formed (the manufactured analog of the mineral bassanite). When water is added, the resulting material (plaster of Paris) can be molded, cast, carved, polished, waxed, and painted.

Oil paintings were created on canvases prepared with gesso, a plaster/glue mixture, then mounted in gilt plaster frames. Plaster completed broken statues (e.g., the second wing of the Nike of Samothrace), and was used to sculpt maquettes and molds for bronze works. (Unlike marble statues, plaster models could be added to and repaired, allowing sculptors to learn from their mistakes.) House paint was mixed with plaster to produce delicate colors, and murals were painted into not-yet-dry plaster walls. Dinosaur bones (and other heavy but delicate artifacts) were brought from distant lands, safe in their jackets of plaster.

But the most important civilizing role plaster has played is in model making and reproduction of three-dimensional items. Every major city park can have its copy of "The Thinker." Broken but scientifically important samples could be completed and mass-produced: e.g., instead of one irreplaceable Neanderthal skull, anthropologists could take measurements from individual copies at their own universities. And in case an original was lost, damaged or destroyed, copies existed to aid in restoration.

Although replaced in many of its functions by other plaster compositions, acrylics, and polymer resins, plaster of Paris was invaluable in spreading scientific and artistic knowledge, especially in the 1800s and 1900s. And Paris, the City of Enlightenment, still sits on the gypsum mines of Montmartre.