LESSON 12: Flashcards
(18 cards)
A single or series of surfaces punctures, holes, or gaps, made by a sharp tool or created by an animal. The size is generally of millimetric to centrimetric scale. Perforations are deeper than wide and penetrate into the body of stone
Perforation
Point like millimetric or sub millimetric shallow cavities. The pits generally have a cylindrical or conical shape and are not interconnected, although transitions patterns to interconnected pits can also be observed
pitting
Discoloration and deposit
1.Crust
2.Deposit
3. discolorization
4. Efflorescence
Generally coherent accumulation of materials on the surface. A crust may include exogenic deposits in cobmbination with materials derived from the stone
Crust
Frequently dark colored but light colors can also be found. Crusts may have an homogenous thickness, and thus replicate the stone surface, or have irregular thickness and disturb the reading of stone surface details
Crust
Sub-type of crust
- Black crust
- Salt crust
Accumulation of exogenic material of variable thickness, some examples: splashes of paint or mortar, sea salt aerosols, atmospheric particles such as soot or dust, remains of conservation materials such as cellulose poultices, blast materials, etc
Deposit
Change of the stone color in one to three of the color parameters: hue, value, and chroma
Discolorization
Corresponds to the most prominent characteristic of a color (blue, red, yellow, orange)
Hue
Corresponds to the darkness (low hues) or lightness (high hues) of a color
Value
Corresponds to purity of a color. High chroma colors look rich and full. Low chroma colors look dull and grayish.
Chroma
Chroma is sometimes called
Saturation
Discolorization relationship with subtract
May affect the surface or be present in depth of stone
(To be preferred to coloring): change in hue, value, and/or gain in chroma
Coloration
(Or fading) gain in value due to chemical weathering of minerals (e.g reduction of iron and manganese compounds) or extraction of coloring matter (leaching, washing out), or loss of polish , y superficial. Dark and bright color marbles often show bleaching as a result of exposure to weather
Bleaching
Corresponds to darkening (lower hue) of a surface due to dampness. The denomination moist area is preferred to moist spot, moist zone or visible damp area
Moist area
Kind of discoloration of limited extent and generally of unattractive appearance
Staining
Generally whitish, powdery or whiskers-like crystals on the surface. Efflorescence’s are generally poorly cohesive and commonly made of soluble salt crystals
Efflorescence
