Stone Dictionary N-R

– N –

Natural Bed — the Setting of the stone on the same plane as it was formed in the ground. This generally applies to all stratified materials.

Natural cleft — this generally pertains to stones which are formed in layers in the ground, When such stones are cleaved or separated along a natural seam the remaining surface is referred to as a natural cleft surface.

Non-Staining mortar — Mortar composed of materials which individually or collectively do not contain material that will stain, usually having a very low alkali content.

– O –

Obsidian — a glassy phase of lava.

Onyx marble — A dense, crystalline form of lime carbonate deposited usually from cold-water solutions. Generally translucent and showing a characteristic layering due to mode of accumulation.

Oolitic limestone — A calcite-cemented calcareous stone formed of shells and shell fragments, practically non-crystalline in character. It is found in massive deposits located almost entirely in Lawrence, Monroe, and Owen Counties, IN, and Alabama, Kansas, and Texas. This limestone is characteristically freestone, without cleavage planes, possessing a remarkable uniformity of composition, texture and structure, It possesses a high internal elasticity, adapting itself without damage to extreme temperature changes.

Opalized — The introduction into a rock of siliceous material in the form of opal, hydrous silicate.

Out of wind — The be out of wind is to have the arris of the stone not in parallel or perpendicular lines. Stone that is out of wind has an irregular or rustic appearance.

– P –

Palletised — A system of stacking stone on wooden pallets. Stone, which comes palletised, is easily moved and transported by modern handling equipment. Palletised stone generally arrives at the job site in better condition than UN-palletised material.

Panel — A finished stone unit used on walls.

Parapet wall — That part of any wall entirely above the roofline.

Parging — Damp-proofing by placing a coast of ½ inch (13mm) setting mortar to the back of stones or the face of the back-up material.

Parquetry — An inlay of stone floors in stones or the face of back-up material.

Paving — Stone used as an exterior-wearing surface, as in patios, walkways, driveways, etc. (see flooring).

Perforated wall — One that contains a considerable number of relatively small openings, often called pierced wall or screen wall.

Perrons — Slabs of stone set on other stones serving as steps and arches in gardens.

Phenocryst — In igneous rocks, the relatively large and conspicuous crystals in a finer-grained matrix or ground mass.

Pilaster — An engaged pier of shallow depth. In classical architecture, it follows the height and width of related columns, with similar base and cap.

Pitched stone — Stone having arris clearly defined; face, however, is roughly cut with pitching chisel used along the line that becomes the arris.

Plinths — The lower square part of the base of a column. A square base or a lower block, as of a pedestal, The base block at the juncture or baseboard and trim around an opening.

Plucked finish — Obtained by rough-planing the surface of stone, breaking or plucking out small particles to give rough texture.

Pointing — The final filling and finishing of mortar joints that have been raked out.

Polished finish — The finest and smoothest finish available in stone characterised by a high lustre (gloss) and strong reflection of incident light, generally only possible on hard, dense materials.

Porphyry — An igneous rock in which relatively large and conspicuous crystal (Phenocryst) are set in a matrix of finer crystals.

Pressure relieving joint — An open horizontal joint below the supporting angle or hanger located at approximately every floor line and not over 15 feet (4.6m) apart horizontally and every 20 to 30 feet (6 to 9m) vertically to prevent the weight from being transmitted to the masonry below, These joints are to be caulked with a resilient non-staining material to prevent moisture penetration.

Processing — The work involved in transforming building stone from quarry blocks to cut or finished stone. This includes primary sawing into slabs, It may also include both hand and mechanical techniques such as sawing, drilling, grinding, honing, polishing and carving.

Projections — This refers to the pulling out of stones in a wall to give an effect of ruggedness. The amount each stone is pulled out can vary between ½ and 1-½ inches (1.3 to 3.8 cm). Stones are either pulled out at the same degree at both ends or sometimes one end is pulled out, leaving the other end flush with the majority of the veneer.

Pumice — An exceptionally cellular, glassy lava resembling a solid froth.

– Q –

Quarry — The location of an operation where a natural deposit f stone is removed from the ground.

Quartz — A silicon dioxide mineral that occurs in colourless and transparent or coloured hexagonal crystals and also in crystalline masses. One of the most common minerals, the chief constituent of sandstone.

Quartzite — A compact granular rock composed of quartz crystals, usually so firmly cemented as to make the mass homogenous. The stone is generally quarried in stratified layers, the surfaces of which are unusually smooth. Its crushing and tensile strengths are extremely high; the colour range is wide.

Quartzitic sandstone — A sandstone with a high concentration of quartz grains and siliceous cement.

Quirt — A groove separating a bed or other moulding from the adjoining numbers.

Quoins — Stone at the corner of a wall emphasised by size, projection, and rustication or by a different finish.

– R –

Range — A course of any thickness that is continued across the entire face. All range courses need not be of the same thickness.

Recess — a sinkages in a wall plane.

Reglet — a narrow, flat moulding of rectangular profile.

Relief or relieve — Ornament in relief. The ornament or figure can be slightly, half, or greatly projected.

Relieving arch — one built over a lintel, flat arch or smaller arch to divert loads, thus relieving the lower member for excessive loading. Also known as discharging or safety arch.

Return — the right angle turn of a moulding.

Return head — stone facing with the finish appearing on both the face and the edge of the same stone, as on the corner of a building.

Reveal — the depth of stone between its outer face and a window or door set in an opening.

Ribbon — narrow bands of rock differing to various degrees in chemical composition and colour from the main body of the slate or stone; in other words, bands.

Rift — the most pronounced (see “grain”) direction of splitting or cleavage of stone. Rift and grain may be obscure, as in some granites, but are important in both quarrying and processing.

Rip rap — irregularly shaped stones used for facing bridge abutments and fills; stones thrown together without order to form a foundation or sustaining walls.

Rise — the heights of tones, generally used in reference to veneer stone.

Rock — an integral part of the earth’s crust composed of an aggregate of grains of one or more minerals. (Stone is the commercial term applied to quarry products.)

Rock (pitch) face — similar to split face, except that the face of the stone is pitched to a given line and plane producing a bold appearance rather than the comparatively straight face obtained in split face.

Rodding — reinforcement of a structurally unsound marble by cementing reinforcing rods into grooves or channels cut into the back of slab.

Roman Arch — semi-circular arch.

Rose window — a circular tone window fitted with carved tracery.

Rough sawn — a marble surface finish accomplished by the gangsawing process.

Rubbed finish — mechanically rubbed for smoother finish.

Rubble — a product term applied to dimension stone used for building purposes, chiefly walls and foundations, and consisting of irregularly shaped pieces, partly trimmed or squared, generally with one split or finished face, and selected and specified with a size range.

Rustication — chamfers or square singings round the face edges of individual stones to create shadows and to give an appearance of greater weight to the lower part of the building. When only the horizontal joints are sunk, the device is known as banded rustication.